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Full text of "Concrete and constructional engineering"

CONCRETE 

AND 

CONSTRUCTIONAL ENGINEERING 



VOL. VII I. 1913. Nos. 1 to 12. 

A MONTHLY JOURNAL FOR ENGINEERS, 
ARCHITECTS, SURVEYORS & CONTRACTORS 
and all interested in CEMENT, CONCRETE, 
REINFORCED CONCRETE, FIRE-RESISTING 
CONSTRUCTION and STRUCTURAL STEEL. 






VOLUME VIII. 



^? 



All Rights Reserved 




Published at North British and Mercantile Building 
Waterloo Place, London, S. W. 



/A 

Digitized by the Internet Archive 

in 2010 with funding from 

University of Toronto 



http://www.archive.org/details/concreteconstruc08lond 



I CONCRETE 

AND 

CONSTRUCTIONAL ENGINEERING 



Volume VIII. 



1913. 



Published at North British and Mercantile Building, 
Waterloo, Place, London, S.W. 

INDEX 



BOOKS, NEW : 

Artistic Bridge Design. By H. G. Tyrell... 67 
Associated Portland Cement Manufacturers 

(1900), Ltd., Booklets of the 442 

Bridges, Reinforced Concrete. By Frederick 

Rings, M.S. A 441 

Building Blocks, Concrete. By Max Keller 28 ., 
Building Construction (Advanced Honours 

Course). By Chas. F. Mitchell, M.S. A. ... 142 
Building Construction, Vol. II. Edited by 

F. M. Simpson, F.R.I.B.A 512 

Building Supervision. By George W. Grey, 

P. A. S.I. 810 

Cassell's Reinforced Concrete ... ... ... 212 

Cement Concrete and Bricks. Ly Alfred B. 

Searle 885 

Cement Specifications, A Treatise on. By 

Jerome Cochran ... ... 361 

Coast Erosion and Protection. By Ernest R. 

Matthews, A.M. Inst. C.E. 733 

Continuous Beams in Reinforced Concrete. 

By Burnard Geen, A. M.I. C.E 512 

Concrete Institute, Transactions of the 213, 389 

Concrete Pocket Book for 1914 884 

Considere System of Reinforced Concrete, 

The ... 602 

Demolition of Concrete and Reinforced 
Concrete Buildings, The. By Ernest 

Schick 884 

Doors, Reinforced Concrete ... ... ... 301 

Eccentrically Loaded Reinforced ( oncrete 
Column., Further Experiments with. By 
Dr. Maximilian Ritter von Thullie ... 441 

Engineering as a Profession. By A. P. M. 

Fleming and R. W. Bailey 736 

Estimating in Reinforced Concrete Work. 

By Dr. A. Kleinlogel 313 

Estimating for Reinforced Concrete Work. 

By T. E. Coleman 212 

Experiments with Fixed Beams. By Dr. 

von Emperger 285 

Fire Prevention. By P. J. McKeon ... ... 61 : 

Fire Protection in Buildings. By Harold 

G. Holt, A.R.I.B.A. -S3 

Fire Tests with Partitions ... ... ... 662 

Fire Tests with Roof Coverings of Asbestos. 
Cement Corrugated Sheets ... ... ... 283 

Fire Tests with Reinforced Concrete Doors Sn 
Flat Plate Theory of Reinforced Concrete 
Floor Slabs. By Henry T. Eddy, C.E. ... 589 

Foundations and Machinery Fixing. By 

Francis H. Davies, A.M.I.E.E 213 

Further Problems in the Theory and Design 
of Structures. Bv Ewart S. Andrews, 

B.Si . I.n,'-'. (London) 587 

General Theory of Reinforced Concrete. By 
Charles Amar ... ... ... ... ... 513 

Handbook of Testing Materials, A. Bv Prof. 

C. A. M. Smith 513 

Investigations of Continuous Structures in 
Reinforced Concrete. By Prof. H. Scheit 
and Dr. E. Probst... ... ... ... ... 590 

Kessler's Fluates. By Hans Hanenschild ... 



883 



51 1 



"42 

141 
141 

-•'4 

283 



Lockwood's Builders' and Contra 

rrice Book lor 1913 

.Manual ol Cement Lesting, A. By W. A. 

Richards and 11. B. North 

Mortar Materials - Cement, Lime and 

Plaster, The Preparation of. B3 P 

Karl Schoch ... ... 

Natural Rock Asphalts and Bitumen.. By 

Arthur Danby ... 

Partitions, Jtire Tests with 
Practical Stone Quarrying. 

Greenwell, A.M. Inst. C.E. , and i. Vincent 

l-.lsden, D.Se. (Loud.) 

Primer of Cement, A. By Dr. Hans Kiihl 
Portland Cement, Its Manufacture, ! 

and Use. By I). B. Lull, r ... 
Properties and Design of Reinforced Con 

crete, The. Bv Nathaniel Martin; B.Si 
Public Works Calculator, The. By a Public 

Works Officer 

Roads and lavements, A I ext Book on. By 

Prof. Frederick P. Spalding 

Street Pavements and Paving Material-. 

By George W. Tillson, C.E 

Structural Design, Elements of. By II .1 

R. Thayer 

Structural Details of Hip and Valley 

Rafters. By Carlton T. Bishop 

Siructural Drafting. By frank O. Dufoui 
spon's Architects' and builders' Price Book 

and Diary 213 

Staircases in Reinforced Concrete and Arti 

ficial Stone. By Karl Matthies 
Jesting of Materials, The. Edited by Prof. 

W. Hinrichson 731 

I\st. of Reinforced Concrete Buildings 

under Load. Bv Arthur X. Talbot anil 

Willie A. Slater" 588, 

r/heory and Design of Structures. By Ewart 

S. Andrews 733 

Wooden Trestle Bridges and I rn 
crete Substitutes, A Treatise on. By 
Woolcott C. Foster 883 

CEMENT: 
Caki d ( 1 it, Some Tests "ii 

( Vint nt as a l'l 1 - 1 \ ati\ e... 

Cement Mixtures. By II. E. Rogers 562 

( lement frail; . 1 he... 

Constitution of Portland Cement, I he. 1 ■ 

P. N. Bat. s 

Portland O mi nt, Its Manufa. tu I sting 

and Use. By D. B. Butler 

Primer of Cement, \. By Dr. Hans Kurd 
Specific Gravity ol Portland Cement, I 

By Pen y ('. H. W. -t 1 1 

Strength 1! C I he. Bj II. C. ) ' 

I i eatise il Ci mi nl Sp. 1 1 ations, A. 

I 1 ' 

CORRESPONDENi 

1 1 Slab Reinfon 1 meni 

l-'ire I'r (nt 'imi and lllt . v 

1 i.n.il 



82 

■54 

Z23 

^97 

i,-,, 

Sig 



597 

5-4 



374 



Reinforced Concrete Failures ... : '»7 

Widening of the Dover Pier, The 5-° 

EDITORIAL NOTES: 

Assouan Dam. The • 

Vctive Concrete Institute, An 

Belgian Natural Cement ... ■•■ ■•■ •■■ 
Building Exhibitions and Reinloreed Con- 
crete , • • " 

Building Trades Exhibition 

Cement Trade, The 

Colliery Work. Concrete lor 

Competition for Concrete Cottages 

Concrete Cottages •-• ■•• 745. 

Concrete Institute, The, Animal General 

Meeting 

Concrete Roads ■ •• ■ •• - •" "t 

Construction of Cotton Mills, The Use ot 

Concrete in the •" 

Government and Reinforced Concrete, I he. 

Buildings for Small Holdings ... . - 

International Association for le-ting 

Materials, The 

Ironmongers ••• . ■•■ ;•■ "■ 

Local Government and Reinloreed Con- 

cretc The ... ■■■ ■•■ *" "' **oj 
London County Council Regulations, The 

52i, 59S, 
London County Council, The Responsibility 

of the 

Obituary Notice ... ■ •• ••■ — — 
Proposed Regulations and Fire Protection, 

The ••■ . ,. •• 

Prussian Building Regulations regarding 

Reinforced Concrete, Some New 

Reinforced Concrete Failures 

Road Bridges of Reinforced Concrete 
Third International Road Congress, The ... 

GENERAL : 

Annual General Meeting, The Concrete 

Institute ••• ■■: 

\polication of Cast Iron in Columns and 
Arched Bridges. By Dr. F. von Emperger. 

A Review ... 

Barge- and Floating Buoys, Concrete 
Beams, Reinforced Concrete. On the Resist- 
ance of Beams Subjected to Flexure. By 
Alfred Fyson, M.Inst.C.E. ... 3°°, 409, 477 

Bridge over the Moldau, The Reinforced 

Concrete. By F. Mencl 39^ 

British-American Tobacco Co., Ltd., New 

Premises ■■■ 747 

Buildings of Concrete and Reinforced Con- 
crete Erected in the International Build- 
ing Exhibition at Leipzig. By Dipl. Ing. 

Philipp Rauer, C.E 53 8 

Building Trades Exhibition, Olympia, The 316 

Cement Mixtures. By H. L. Rogers 562 

Cement Plant in Vancouver, New 764 

Chertsey Lock 449 

Coal Washing Plant for the Old Silkstone 
Collieries, Ltd., A Reinforced Concrete... 856 
i< rete Blocks and Tiles in Norfolk ... 789 

Concrete Institute, The 45. '-4. 

195, 263, 283, 3jo, 383, 427, 468, 500, 571, 842 
1 1. Road Construction. By A. N. 

Johnson 45 e 

idence (See Correspondence). 

Cottages, Com rete Block 7 s ') 

Cottages and Farm Buildings 71, 288, '143. 789 
Cottages in South Wales, Concrete ... 
Cotton Mills, Concrete in By Harold G 

Holt, A.R.I.B.A 610, 711. 

Cracks in Concrete and Surface Treatment 
Dock Construction, Reinforced Com rete in. 

By I R. Matthews, A.M.Inst.C.E. ... 461 

Dome, \n Interesting Reinforced Concrete. 

Bj I 'i V Kleinlogel ... 39 

L) ,11. 1 Public Library, Melbourne, Rein 

1 ireed Concrete. By Albert Lakeman tfei 

Duisburg, New Municipal Theatre in By 

Viktor Mautm r 

Economical Slab Reinforcement. By II. 

Kruse, C.E 54O 

Economical Slab Reinforcement. By John 

A. Davenport, M.S... A M.In 1 C E. ... 166 

ii. and Reinfon 1 d Con 
.1 ti at thi Intel rial ional Bui Id ing Exhi- 
bition, Leipzig ... 633 



46S 



491 



8 - 



299 



Extension ot Works, Siemens Bros. & Co., 
Woolwich. By F. Southey, A.M.Inst.C.E. 85 

Glasgow Building Exhibition ... ... ... 792 

Glass Warehouse at St. Helens, Reinforced 
Concrete 

drain Elevators in Canada, Concrete. By 
B. J. Weller 190 

Grand Stand for the Public School, Athletic 
Field, Brooklyn, New York, Reinloreed 
Concrete. By Harold L. Alt 341 

Gross-Lichterfelde Testing Station, The 
Work of the 256 

Guard Rails in Road Building, Reinforced 
Concrete ... ■•■ •■■ •■■ 866 

Harrod's Depository, Barnes 225 

Impermeability Tests on Concrete. By 
James L. Davis 112 

Institution of Civil Engineers and Rein- 
forced Concrete, The ... ... ... ... 827 

International Building Exhibition at 
Leipzig. By Ph. Rauer, C.E. 176,538,633 

International Road Congress, The Third 456, 571 

Lining of the Main Canal of the Boise 
Irrigation Project, U.S.A., Concrete. By 
F. W. Hanna ... ... ... 552 

London's Reinforced Concrete Regulations. 
By H. Kempton Dyson 530, 599, 682 

Machine Room for the Calico Printers' 
Association, Ltd., Manchester, Concrete 
Block 473 

Measurement of Concrete Work, Proposed 
Standard Methods for the 

Middlesex Guildhall, The. By Albert Lake- 
man 

National Association of Cement UJsers, 
U.S.A., Cement and Concrete at the 

252, 650, 723, 797 

\< 1 t ssity of Imposing the R.I.B.A. Rules 
for the Calculation of Reinforced Concrete 
Works in Competition. By Maurice Behar, 
M.C.I. 755 

New Stationery Office ... ... ... ... 5 

Office Premises. New Street, Birmingham... 525 

Old Silkstone Collieries, Ltd., A Reinforced 
Concrete Coal Washing Plant for the ... 856 

Ornamentation in America, The Use of 
Concrete for ... ... ... ... ... 119 

Patents Relating to Concrete, Recent 
Briti-h ... ... ... ... 246,694 

Pavement-, Methods and Cost of Construc- 
tion, Concrete. By Carl M. Boynton ... 419 

Practical .Design of Reinforced Concrete 
Flat Slabs, The. By Sanford E. Thompson 27 

Presidential Address, The Concrete Insti- 
tute. By E. P. Wells, J.P 842 

Prewitt Reservoir Project, U.S.A. ... ... 701 

Pons Perilis Bridge 488 

Port of London, Some Improvements in the. 
By Albert Lakeman 671 

Problems in the Theory of Construction. 
The Oblique Loading of Beams and 
Columns. By Ewart S. Andrews, B.Sc. 
Eng. (Lond.) 233 

Provision Warehouse in Reinforced Con- 
crete 330 

Rebuilding of a Highway Bridge known a> 
Pons Perilis over the River Brue ... ... 488 

Recent Examples of Reinforced Concrete in 
South Africa, Some ... 2.-8 

Recent Reinforced Concrete Construction in 
Alexandria. By T. D. Key ;8 

Roads and Footways, Concrete. Bv E. R. 

Matthews, A.M.Inst.C.E 171 

Roads oi Wayne County, U.S.A., Concrete. 

By Edward N. Hines S 

Royal Agricultural Show, Bristol, Ccnu nt 

and Concrete at the 646 

Saint Louis. Senega], Reinforced Com 

Wharf and Jetty at too 

Sea Walling on the Trestle System, R<in 

Forced I 'oncrete 5-0 

.sic mi us Bros. jfc Co., Woolwich, Extension 

of Works 85 

S >utli l.acnli. ill Goods I >. p6t. By Alb< it 

Lakeman ... ... ... ... 375 

Specific Gravity oi Portland Cement, II 

By Percy C. II. West . 1 

Stopping Plan<s in Reinforced Concrete By 

Edward J. Stead, A.M.Inst.C.E .'. 96 

Surface Treatment of Concrete, R t 1 >< n 1 on s 
\i embei . I a< toi y Buildings 
Buill with ir); 



157 



619 

403 



187 






Wall Footings and Columns, Reini 1 

Concrete ■•■ , ■•• , ••; 

Waterford Bridge, 1 In , By Vlbert Lakeman 

W.u, rproofing foi I »n« rete, 1 ■ ts ol ... 

Waterproofing Qualities of Oil-mixed 
C >m i' i' ■ By Logan Waller Page ... ... 

\\ idening of tin- Dover Pier, 11k-. By 
A. 1. Walmisley, M.Inst.C.I 

[NDUSTRIAL NOTES : 

Separators 

Triangle Mesh, Concreti Reinforcement ... 

LAW CAS1 
Shuman's Concrete Pile Patent Upheld 

MEMORANDA 
Agricultural Society's Show, Doncaster 
Alexandria, Recent Reinforced Concrete 

Work- in 

American Concrete Institute 

Anglo-American Exposition (1914) 

Application of Reinforced Concrete to 

Rural Housing, The •• 

Bridge at Guildford, A Reinforced Con- 
crete ;• ••■ •■■ 

British Fire Prevention Committees lest- 

ing Station, The 293, 3<j8 

British Museum, Reinforced Concrete at the 
Buildings on Reinforced Concrete Raft ... 
Building Trades Exhibition, Olympia 

Caked Cement, Some Tests on 

Catalogues 222,295,81 

Cathedral at Port an Prince 88 

Cement Top Floors, Specification for ... 14 

Cement as a Preservative 74 

Chimney of Interesting Design, Concrete ... 21 
City and Guilds of London Institute 

Coal Tips, Reinforced Concrete for 

Cold Storage Building, Reinforced Concrete 

Competition for Designers 

Concrete Block Garage, A Cheap 

Concrete Column, A Very Large Reinforced 

Concrete Houses 

Concrete Institute, The 217,443,814, 

Concrete Reflectors for Lamps 

Concrete Scow, A 

Concrete Trestle 

Concrete versus Wooden Poles 

Contracts 

Cornell University, Concrete Tests at 

Cottages in South Wales, Concrete 

Cotton Warehouses in U.S.A., Large R. in- 
forced Concrete 

Crane Pontoon in Reinforced Concrete 
Disadvantages of a Hardwood Floor over 

Concrete ... ■■■ •■• .•■• 

Designing Diagram for Cantilever Rein- 
forced Concrete Retaining Walls 

Dundee, New Wharf in Reinforced Con- 
crete for 

Enquiries I 5 2 > 

Erratum Notices 293, 5 2 °> 

Fence Posts, Reinforced Concrete 

Fire Protection in Theatres 

floor, for Foundries, Concrete 

Garage, A Cheap Concrete Block 

House-, Concrete ... ■ •• 

How to Patch a Concrete Floor 

Hypochlorite Solution Tank-, Reinforced 

Concrete for 
Improvements at Havre, France 
Institution of Municipal Engineers 



146 



for 
The 



Testing 



75 

293 
519 



147 
667 

149 

219 

368 
295 
818 
151 
368 
149 
743 
593 
71 



146 

815 



International Association 
Materials, The 

International Road Congres 

loints, The Use of 

Landslides, Suggested Methods of Pre- 
venting 

Lining a Deep Shaft with Concrete 

Locomotive Coaling Station 

London County Council School of Building 

Manchester Municipal School of Technology 

Manchester Ship Canal Co., The. Transit 
Sheds 

Merrion Pier Scheme, Pembrokeshire 

Mexican Annals of Public Works, The 

Mine Airways, Concrete in 

Municipal Engineers, Institution of 

National Physical Laboratory, The 



59i 
443 

593 



1 1' 



148 
815 

517 



Newpoi t l'o i i 

m, South K. 

X 1 v. S 1 

I i 11 

1 I 1 Building, A Ri i 

1 !om rete 

( >p< 1.1 I louse in R 
( (yster Sin II, I 
Pillar B 

Portland Cement lot Roofing 

Pn ur< I > -t in W( t ' 

Producing Pol ishi .1 Effe< ts on ( 

Work ... 

Purification oi Watei Supply, Aberdeen 
Raising Reinforced C te Walls with 

Jacks ... ... ... ... 

Reflectors for Lamps, C 

Reinfori' I < om 1 te for Coal Tips 

Reinfon ed Coin rete in the P 
Again-t Hostile Aircraft at the Naval 
Magazine, Portsmouth 

Repairing St. Paul's 

Repair Work, Concrete for 

R.I.B.A., The ... 

Rockwork at the Zoological Card 
crete ... ... 

Roofing, Portland Cement for 

Royal Technical College Arch 

Craftsmen's Society, Glasgow 

San Francisco Station 

Science Museum at South Kensington, New 

Scottish Junior Gas Association 

Scow, A Concrete 

Society of Engineers' Status Priz •, Th ■ 

Society of Engineers (Incorporated), 11" :: 

South Western Polytechnic, The 

Strength Coefficients of Reinforced Con- 
crete Telegraph Posts 

Tables of Reinforced Concrete 

Tar and Cement Pavements in Germany 

Temperature Changes in Concrete when 
Setting 

Trade Notices 79,80. 

152, 221, 293, 372, 445, 520, 593, 815 

Trestles, Concrete 

Uruguay 

Walls for Fruit Growing, Concrete 

Warrington Bridge 

Westminster Technical Institute 

Working Class Housing, A Prop 

for 



7li 



14' 



1 17 
75 



v. ' 
U7 

1 V) 



815 






146 



NEW WORKS IN CONCRETE AT HOME AND 
ABROAD : 



Bandstand, An Artistic Concrete 

Beacon for Alexandria, New 

Boat Shelter, "Roath Park Lake, Cardiff 

Bridge, Ballingdon, Suffolk 

Bridge in California, Reinforced ( 
Bridge in France, Reinforced Concrete 

Bridges in India, Some Concrete 

Bridge Over the Periyar, Travancore, Rein- 
forced Concrete 

Chapel at Lossiemouth, A Concrete Stone ... 

Clevedon, Pier Landing Stage 

Coal Bunkers at Lame, Ireland, Reinforced 

Concrete 

Coal Hoppers at Oughterside, Cumberland 

Concrete Block Wall at Shand 

Concrete Bricks. A House of 

Covering of Two Service Reservoirs in 

Reinforced Concrete for the Aberdeen 

Waterworks 

Dam at Hongay, French Indo-China, Rem 

forced Concrete 

Egypt, Concrete in ... ... •■■ ■■ _ ■•• 

Extensions to Electricity Works, n 

poration, Reinforced Concrete 
Floors and Flat- in the New Polio 

at Goodwick, Reinforced Concrete 
Houses in a Chicago Suburb, Some C 
Hotel Building. Reinl 
Hotel in the Philippine-, A Reinforced 

Concrete 

Incinerator, A Reinforced Concrete 

Lagos, Th.- New General Post Offi© 
I iv,'rp,>ol Daily Post, New Offices 
Market Wayne, I 

Concrete .. 

Middle-I '. ugh, New Bu in Pi 

Reinf »rced Co te at 

' .madiau Factory, A 



1;') 

1 w 
510 

- 

S s 
584 

ss. 



:-'i 












Milan, New General Post Office, The 

da at Wynyard Park 

Pier Landing Stage at Clevedon 

Posts at Grovelands Park, Reinforced Con- 
crete ... •■• ■••_ . ••■ 

Quay Front at Westport, Ireland, Rem- 
forced Concrete 

Retaining Wall, A Reinforced Concrete ... 

Rising Main, A Reinforced Concrete 

Safety Device for Tunnel Work 

St. Mary's Church, Horden 

St. Mary's College, Gahvay 65S 

St. Marv's Presbytery, Stockton on-Ti 

Tank at'a Current Meter Rating Station at 
Calgary, A Reinforced Concrete 

Tenement Houses, Double 

Test House, Weigh Cabin and Private 
Office, Concrete Block 

Tinplate Work-. Llanelly, South Wal 

Transit Sheds. The Manchester Ship Canal 

Warrington Bridge 

Water Tower at Scopwick, Reinforced Con- 
crete ... ... ■•• ■■• 

POPULAR USES : 

Cottages, Concrete 

Cooling Vat, Home-made 

Farmstead at Bonsauvcur Convent, Dun- 

garvan, Ireland, A Model 

Protecting Drinking Water 

Tennis Court, Reinforced Concrete 

Wind-Break Fence-, Concrete 

RECENT VIEWS ON CONCRETE AND 

ENFORCED CONCRETE : 

Action of Acids, Oils and Fats upon Con- 
crete. By W. Lawrence Gadd, F.I.C., 
M.C.I. 

Hills of Quantities for Reinforced Con- 
crete. By John M. Theobald, F.S.I. 

Canton-Kowloon Railwav : Chinese Section, 
The. By Frank Grove. M.Inst.C.E., and 
Basil T. B. Boothby, A.M. Inst. C.E. 

Concrete in its Legal Aspect. By W 
Valentine Ball 

Constitution of Portland Cement, The. Some- 
Results Obtained at the Experimental 
Cement Plant of the Bureau of Standards. 
By P. H. Bates 

Construction of the Roadways on Bridges 
and Viaducts By Emil Heidecker 

Economy in Reinforced Concrete Design. 
By John A. Davenport 

Fixed or Movable Bridge-, Su-pension 
Bridges, and Bridges with Railway Lines. 
By A. S. Tanenbaum 

Practical Examples of the Use of Concrete 
at Collieries. By John Gregory 

Props and Beam' in Mines. By S. M. 
Dixon, M.A., etc. 

Relative Activity of Grains of Cement 
according to their Fineness, The. By R. 
Feret 

R< servoirs for Water and Petroleum, Con- 
crete. By J. I.. Jeff ry. A.R.S.M 

I and Gravel Washing Plants. By 

Raymond W. Dull 

Solid- in Water and its 
Bearing on Concrete Work, The. By Dr 

J. s. Ow< ... A.M.Inst.C.I 

ick Chimn ys, ( )n the. By 
Harold Can 

tidings in London. By S 
" ... 

Strength <>f Cement, The. By II. ('. Johnson 

Third Inti rna t ional Road I 1 156, 

Type. ..I Surfacing to be adopted on Bridgi . 
Viadui t-, • i. Repi rt. By II. Howard 
Humphreys, M.Inst.C.E., and W. I. 
Taylor ... 

! ■ Bureau Yard . 

d D01 , U.S. Na y Bj II I: - 

ford 

"While Star" Dock and the Adjoining 
Quays at Southampton, I I isl ru< - 

Bj I I Wi . 'v. irtb Sheilds, 
1 1 . 1 1 



139 

507 



364 



808 
139 



201 



650 

573 



7"9 



REINFI >RCED CONCRETE : 

Alexandria, Recent Reinforced Concrete 

Construction in. By T. D. Key 

Beams, Reinforced Concrete, On the Resi-t- 
ance of Beams Subjected to Flexure. By 
Allied Fy-011. M.Inst.C.E. ... jo 

BilK of Quantities for Reinforced Concrete. 
By John M. Theobald, F.S.I., M.C.I. ... 

Bridge over the Moldau, The Reinforced 
Concrete. By F. Mencl 

Bridge Over the Periyar, Travancore, Rein- 
forced Concrete ... 

Coal Bunkers at Larne, Ireland, Reinforced 
Concrete 

Coal Hoppers at Oughterside, Cumberland, 
P.einforced Concrete ... 

Coal Washing Plant for the Old Silkstone 
Collieries, Ltd., A Reinforced Concrete ... 

Dam at Hongay, French Indo-China, Rein- 
forced Concrete 

Dock Construction, Reinforced Concrete in. 
By E. R. Matthews, A.M. Inst. C.E. 

Dome, An Interesting Reinforced Concrete. 
By Dr. A. Kleinlogel 

Dome of Public Library, Melbourne, Rein- 
forced Concrete. By Albert Lakeman ... 

Economy in Reinforced Concrete Design. By 
John A. Davenport 

Floors and Flat- in the Xew Police Station 
at Goodwick, Reinforced Concrete 

Glass Ware.bou-e at St. Helens, Reinforced 
Concrete 

Grand Stand for the Public School Athletic 
Field, Brooklyn, Xew York, Reinforced 
Concrete. By Harold L. Alt 

Guard Rails in Road Building, Reinforced 
Concrete 

Hotel Building, Reinforced Concrete... 

Institution of Civil Engineers and Rein- 
forced Concrete, The 

London's Reinforced Concrete Regulations. 
By H. Kempton Dyson ... ... 530. 599. 

New Premises, British-American Tobacco 
Co., Ltd.. Reinforced Concrete 

Practical Design of Reinforced Concrete 
Flat Slabs, The. By Sanford E. Thompson 

Posts at Grovelands Park, Reinforced 
Concrete 

Provision Warehouse in Reinforced Con- 
crete 

Quay Front at Westport, Ireland, Rein- 
forced Concrete 

Sea Walling on the Trestle System, Rein- 
forced Concrete 

South Africa, Some Recent Example- of 
Reinforced Concrete Construction in 

>• 1 iping Planes in Reinforced Concrete. 
By Edward J. Stead, A.M.Inst.C.E. 

Theatre in Duisburg, Reinforced Concrete 
Xtw Municipal 

Wall Footings and Columns, Reinforced 
Concrete ... 

Wharf and Jetty at St. Louis, Senegal, 
Reinforced Concrete 



39 2 
584 

726 
729 
851 
439 
461 
39 
821 
350 
436 
626 



v 
730 



564 

55g 

06 

781 

S-19 



TESTS : 

Caked Cement, Sonic Tc-ts on 

Column, A Very Large Reinforced Concrete 

1 11 University, Concrete Tests at 
Doors. Reinforced Concrete 
Experimi nts on the V if Old and 

Concrete. By Hector St. George 

Robinson 
Fire rests with Reinforced Concrete Doors 
I rests with Roof Coverings oi Asbestos 

Ci no :it Corrugated Shi ets 

I Beams, Experiments with 

Gross-Lichterfelde Testing Station. I h< 

Work of the 

Impermeability I 1 1 in Concrete. By 

L. Davis 

National Physical Laboratory, The 

Partitii 11-. Fire Tests with ' 

1 ' I est in Wet Concrete 

1 Waterpi oofing foi * !oni o t< 



665 
.•18 
5»9 



184 
811 






1 13 

5"7 



6 



CONCRETE, 

AND 

CONSTRUCTIONAL ENGINEERING 



Volume VIII. No. 1. London, January, 1913. 

EDITORIAL NOTES. 



THE RESPONSIBILITY OF THE LONDON COUNTY COUNCIL. 

In our previous issue we dealt at some length with the question of the large 
number of existing buildings in the metropolis that do not comply with 
the requirements of the Building Acts (Amendment) Act of 1905 as far as 
safety from fire is concerned, and — as we anticipated — a vast amount of argu- 
ment and correspondence — both confirmative and the reverse — has arisen from 
what we published. Not only have we been the recipients of numerous com- 
munications on the matter, but we see that both the daily and the technical 
Press in general have now accorded space to the subject editorially and bv the 
insertion of letters, although none have perhaps " called a spade a spade " 
quite as plainly as we have. For the considerable amount of valuable support 
received from our contemporaries we would here immediately tender our best 
thanks. 

Again, in the council chamber of the London County Council, of the Ken- 
sington Borough Council, and of other corporate bodies, the subject-matter 
of our editorial has been under comment. If we are rightly informed, there 
has even been a deputation on behalf of the shop assistants in the matter before 
the Building Act Committee at Spring Gardens. But for all this, there has 
been no definite public declaration on the County Council's behalf that the 
present lamentable state of affairs is to be remedied, and that the public is to 
be safeguarded in such a manner as was intended under the Building Act 
referred to. 

It thus behoves us again to call the attention of the members of the London 
County Council and other authorities to the extraordinary scandal in our 
midst, for which, up to the present, the spokesmen of the London County 
Council have apparently been only anxious to find excuses, but have not 
promised prompt and effective remedy. 

There is one point in particular that we must deal with next — we spoke 
of some 50,000 buildings awaiting attention, i.e., buildings under the self-same 
Section 9 of the Building Acts (Amendment) Act of 1905, under which premises 
like those of Messrs. Barker come. We pointed out that not one thousand of 
these cases had, so far, been put in order in the intervening seven years. We 
gave the Council even greater credit than necessary — the exact number to June 
last was only 527. But, further, it would now appear, instead of 1 
to deal with 50,000, there are actually somewhere between 93, 



THE RESPONSIBILITY OF THE L.C.C. 



[CONCRETE ] 



structures awaiting the Council's pleasure, for, in addition to those under 
Section 9, there is now official evidence available that no fewer than 48,566 < ases 

have been duly notified to the London Count}' Council under Sections 10 to 12, 
and that only 351 under Section n, and 4,43c under Sections 10 and 12, have 
so far been put in order, or exempted from the operation of the Act. In other 
words, close on 44,000 cases are awaiting- attention under the three further 
sections of the Act. 

THE EXISTIXG POWERS. 

To make ourselves quite clear, we would remind our readers that there is 
a Section 9 that affects buildings that are tall, or in which more than twenty 
people " live " or are employed. There is Section 10 that relates to projecting 
shops ; a Section 11 that relates to certain dangerous stores; and a Section 12 
affecting a number of minor structures. The buildings under Sections 9 and 10 
are those most in the public eye. For those under Section 9 it required seven 
years to put 527 buildings in order, and under Sections 10 to 12 it has required 
seven vears to put into proper order, or exempt, some 4,781 cases. We wonder 
if the public realises what this rate of progress means, for it would almost seem 
that five centuries would he required to deal with the buddings under Section 9, 
and quite half a century to deal with those under otlier sections named. 

Xow in a communication which we print in another column (page 64), the 
figures are not only summarised and confirmed, but the causes of the existing 
state of affairs indicated, and certain useful suggestions are made as to the 
remedy. 

SOME SUGGESTIONS. 

We offer no comment on the causes. They are public knowledge. As to 
the suggestions, we give them here seriatim, with an expression of opinion 
that they are feasible and economic, and would, if adopted, give us safer 
buildings without undue delay. Thev read as follows : — 

(a) A public announcement in the Press (to be repeated monthly) that it intends 
to have the whole of the work under the Building Acts (Amendment) Act of 
1905 remedied by January 1st, 1918, the public announcement to be followed 
by two circular notices in the 44,000 notified cases under Sections 10 to 12. 

(b) An immediate instruction to the District Surveyors to notify to the Council, 
say within six months (as set out in Section 17) all cases they consider to come 
under Section 9 — a matter that has been practically neglected during the past 
seven years — and immediately upon receipt of these notifications an issue of 
two circular notices to owners concerned that the Council are prepared to 
receive suggestions accompanied by plans with proposals as to convenient 
dates for carrying out the necessary structural improvements, and are prepared 
to, assist in every possible way applicants who volunteer plans and offer practical 
remedies. The circular notices should indicate certain primary principles 
desired by the Council, such as alternative routes of exit from workshops and 
dormitories. 

(c) A cancellation of the existing embargo that the fiftv District Surveyi rs are not 
to press the execution of work under Sections 10 to 12 in their respective 
districts, and in place of that embargo an instruction that they shall see that 
the whole of this work is carried out by [918 or earlier, the instruction to set 
out certain guiding principles as to remedies and also grounds for exemption. 
As to exempt ions, any recommendation for exemption signed by the local 
District Surveyor mid two adjoining District Surveyors should 1» accepted 
ipso facto by the Building Act Committee as a prima facie case for exemption 
without further investigation or expense. 



t &£^SEebimv^1 the responsibility of the l.c.c. 



((/) The energetic enforcement in [913 by legal proceedings of at least one 
notoriously bad case under Section 9 and one under Section io in each di 
as an earnest of the Council's intentions. 

(el The formation of several Sub-Committees of three in the Building Acl 
mittee to sit weekly to accelerate the decisions requiring the Commit 
attention under the [905 Act, with the necessary strengthening of the Superin- 
tending Architect's personal staff and the staff of the Committee Clerk. 

(/) The immediate strengthening of the " Escape" branch in the Building Act 
Department by five managing assistants, twenty senior assistants, tw* 
junior assistants, and twenty clerks, etc., all on the temporary establishment, 
tile staff tti work by areas, and each senior assistant to follow his own case from 
beginning to end, all modern mechanical equipment and facilities to be use< 
accelerate the work, including photography and mechanical copying instead of 
tracing. 

(g) The publication quarterly of a list of building owners who have complied with 
the Building Acts (Amendment) Act of 11105 and the addresses of the buildings 
that have been put in order. 

In conclusion, we would only emphasise the necessity of prompt action on 
the Council's part. Otherwise the Council may unexpectedly find its functions 
largely superseded in this particular direction in a manner least expected. Lon- 
don cannot be allowed to stand as an instance of sluggish administration in 
matters of public safety, lor it happens to be the Imperial capital of an Empire 
to which other municipalities should look up to, not the reverse. 

"IRONMONGERS." 

According to Webster's dictionary of the English language, an ironmonger is 
a "dealer in iron or hardware," and hardware is "the general name for all 
articles made of iron." 

Under this definition several distinguished presiding officers of corpora- 
tions, such as the Institution of Civil Engineers, or the Iron and Steel Institute, 
would from time to time certainly come. Yet, if their vocation were so 
described by their fellow officers, or by any individual member of these institu- 
tions, the} - would no doubt resent it as something derogatory, no matter how 
estimable ironmongers as a class may be. 

At the Concrete Institute, at two of its recent meetings, the term " iron- 
monger " was bandied about in this derogatory sense, with a view to describing 
concrete specialists generally, and particularly such specialists who sell reinforc- 
ing bars and other accessories for the construction of reinforced concrete 
buildings. Now, if the proceedings of the Concrete Institute were private, there 
is no reason why individual members of council should not give full express, on 
to their views; but the proceedings being public, such views and classifications 
do not add either to the dignity of the institution concerned, nor do they assist 
in furthering the subjects there under review or advance the status of those 
concerned, be they members of the technical professions in the highesl sense, 
captains of industry, or the lesser lights of the commercial firmament. 

The Concrete Institute is wisely constituted of professional men in the 
highest sense, professional men connected with the industries concerned, and 
others engaged in the execution of contracts for the erection ol structures, 
the purveying of materials necessary thereto. It is only by active, c< 
operation between the different elements concerned that an advance i 



" ironmongers:- [CONCRETE ) 

be made, either in the scientific investigation or practical application of concrete 
or reinforced concrete, a subject essentially dependent on the results of science- 
CMra-industry. The Institute was formed solely by the co-operation of these 
two elements, for those concerned purely in the industrial side are far too 
jealous of one another to allow of their cohesion as a separate entity, and even if 
such a cohesion were possible, their views would have as little weight with the 
world at large as that of any of the other very estimable, but purely ex parte, 
industrial associations. 

Again, the professional and scientific side of the Institute's work would lose 
immeasurably bv the absence of co-operation from the commercial element which 
includes men of considerable technical eminence arid experience. 

For either element to commence to wrangle with the other, because there 
happen to be a few black sheep, is regrettable — the black sheep, it should be 
added, being common to both elements — and the sooner unseemly differences 
of this description are relegated to oblivion the better for the advancement of 
concrete and reinforced concrete and the progress of the Concrete Institute in 
particular. 



E 



, CONSTRUCTIONAL 
ENGINEERING — , 



H.M. NEW STATIONERY OFFICE. 






H.M. NEW 
STATIONERY OFFICE. 




■fr* 



The new Stationery Office for H.M. Office of Works 
'will, •when completed, rank among the largest reinforced 
concrete structures erected in England. There are many 
points of special interest in this building, and not least 
among them the steel gantry employed in its construction. We hope at a later period to supple- 
ment the present article ty a further one dealing ■with the structure ivhen it is more advanced. 
This article has been prepared for us by Mr. Albert Lakeman, Hon. Medallist Construction. — ED. 



This new building is highly important from a constructional point of view, 
as the methods employed are quite unique, as will be seen from the accompanying 
photographic views. 1 he fact that reinforced concrete is adopted by the 
Government for a structure of this magnitude is evidence of the almost universal 
opinion that it is by far the most suitable material where fire-resistance, 
economy, and rapid erection are the primary considerations. 

The whole scheme consists practically of two blocks, the smaller of which 
is to be used as offices and the larger as a warehouse, a portion of which will 
be devoted to H.M. Office of Works. Some idea of the magnitude of the 
building, which has been designed by Mr. R. j. Allison, A.R.I. B. A., 
Architect, H.M. Office of Works, can be gathered from the general 
dimensions, which are as follows : — Frontage to Stamford Street, 323 ft., 
to Cornwall Road 189 ft., to Doon Street 377 ft., and to Waterloo 
Road 106 ft. The site is practically an island one, with the exception that 
a large portion at the south-west corner is occupied by the Royal Waterloo 
Hospital for Women and Children, and a small street called Bazon Street cuts 
between the office and warehouse blocks and gives access to the back entrance 
of the hospital. The two blocks will be connected, however, by a bridge which 
is 40 ft. wide, and constitutes practically a building above the first-floor level. 
The average height of the main front walls above the pavement level will be 
77 ft., and there are seven floors in the warehouse portion and eight floors in 
the office block, including the sub-ground and basement, the height generally 
from floor to floor being 10 ft. 6 in. in the former and 11 ft. in the latter. The 
present contract provides for a floor area of about 380,000 superficial feet, 
but an extension has been arranged for consisting of a fifth floor and the cover- 
ing of one corner of the site adjacent to Doon Street and Cornwall Road, which 
will provide a further 100,000 superficial feet, or a total of roughly eleven 
acres for the complete scheme. The general disposition of the ground floor is 
shown on the plan illustrated in Fig. 1, where the complete scheme is given. 
It will be seen that three large internal areas are provided in the warehouse for 
lighting purposes, and there are two in the office block. A covered loadii 
and platform is provided adjacent to Doon Street, and the good 
handled here and despatched to the various parts of the building 



H.M. NEW STATIONERY OFFICE. 



[ QQNCBETEi 



° V °0 7 7 VA | 



A' t/Oj 




3 < 
2 H 



fa S 



0l /O& 00103-lW 



\>,C0NSTPIK"T10NA1.1 
A ENGlMt-ERlNG — J 



H.M. NEW STATIONERY OFFi 




H.M. NEW STATIONERY OFFICE- 



[CONCRETE] 



eight electric lifts, which are situated at the back of the platform. A smaller 
loading yard and platform will be provided at the X.E. angle of the site. This 
end of the building will be arranged for use by H.M. Office of Works Stores 
Dept., and two additional lifts will be provided. In addition to these ten lifts 




,e2 





1 ll 


1 — 1 



c z 

a 2 

3 H 



£ ■ 



there are two for passengers— one in the warehouse and one in the office block 
—and also a goods lift in the latter to supply the top floor, where a large dining- 
room and kitchen are provided for the accommodation of the staff. The whole 
building will be heated by hoi water under forced circulation, and the drainage 
will be earned by cast-iron pipes laid under the basement floor. 

I') the execution of the work a unique feature is provided bv the use 
ol steel gantries, which are shown in the photographic views; and, although 
these a>v used in modern shipbuilding, it is safe to say that this is the first 



1 



CONSTPin.-noNAL 



H.M. NEW STATIONERY ( 



instance in which they have been vised in building work. These gantries ha 
in fact, been modelled on the lines of those used in shipyards, and il i 
believed thai they will effect economy in time and expenditure as compared 
with the usual type of derrick crane. It will he interesting ;is an experimenl 
to see how far the hopes of the designers are realised, and it will certainly be 
found extremely convenient to have tin- whole site practically unobstructed and 
available for working at all times. 




Fig. 4. View showing Concrete Mixer at work. 
H.M. New Stationery Office. 



The vertical lattice members of the gantry are placed in three rows at 
distances apart of 81 ft., 66ft., and 66ft., and the cross girders are built up 
of steel sections in open lattice type, used in pairs, well braced across th< 
and stiffened by diagonal struts between each pair to give strong and light 
design. Electrically-driven travellers run over and serve the whole 
they are each capable of hoisting or lowering and of travelling in t 
or longitudinal directions. They can handle 300 cubic yards per 1 
are capable of lifting the full load of 30 cwts. ; and while carrying t 



H.M. NEW STATIONERY OFFICE. 



[CONCRETE] 




can lift at 150 ft. per 
minute and travel cross- 
ways at 150 ft. per 
minute, or longitudinally 
at 480 ft. per minute. 
A powerful automatic 
brake is provided, cap- 
able of sustaining' tin- 
load, and arranged for 
lowering by gravity ; 
and there is a foot-lever 
brake for controlling the 
longitudinal movement 
of the crane. A platform 
with hand-railing is pro- 
vided alongside one of 
the cross girders, and the 
controllers are placed 
in a cage fixed under- 
neath the cross girders. 
The erection gantries 
were put up by means of 
small derrick cranes, 
which travelled in 
trenches, the upright and 
longitudinal members 
being erected in the first 
instance, and the end 
girders being then pulled 
up by little cranes at the 
top, which will remain 
in position and be util- 
ised in the taking down : 
the girders being re- 
moved in the first 
instance and the uprights 
being taken down in 
sections. 

The building itself 
is being erected on the 
Hennebique system, de- 
signed by Messrs. L. (i. 
Mouchel and Partners, 
Ltd., and the whole of 
the concrete i> being 
machine-m i x e d \\ i t h 
thr< e Ransorrie patent 



[&^ESg~] HM. NEW STATIONERY 0F1 

concrete mixers, one of which is illustrated in Fig. 4. The soil was fou 
1).- composed of 10 ft. of made earth with about [6 ft. of gravel underneath 
ing on blue clay, and the whole of the foundations are taken down well 
the gravel soil and designed to give a maximum pressure of 3 tons per square 
foot. I'lu bases to the columns are carried down generally to a depth of 
about 8 It. below the basement floor level, and these are octagonal on plan, 
as illustrated on Fig. 5. This is a most economical form and it has a maximum 
thickness of 2 ft. 9 in. adjacent to the column, splayed down to 4 in. at the 
extreme outer edges in the particular example illustrated, while the greatest 
width shown at L in the diagram is about 10 ft. The disposition of the 
reinforcement is sufficiently clearly shown to need no detailed explanation, as is 
also the method of taking" the vertical lines of reinforcement into the foundation 
slab. Very few of the foundation slabs were square, and in all such cases the 
loads were comparatively small. 

The retaining- walls, generally speaking, are formed with 6-in. slabs, 
stiffened by horizontal beams at the top and bottom and with counterfort:' 
about 7 ft. apart, while short cross walls are carried back to the columns 
supporting the outside walls, which are spaced at intervals of about 20 ft. The 
height of the walls vary considerably owing" to the different level of the roads, 
but the same principle of construction is employed throughout. The columns 
are spaced generally in rows 20 ft. apart at intervals of 15 ft. 2 in., and som 
typical details are illustrated in Fig. 3, where it will be seen that the size of the 
ground floor varied from 20 in. square to 27, in. square, with eight to twelve 
lines of vertical reinforcement well tied with links, 10 in. apart, in all directions. 
A typical connection between the columns is also giver, showing how the bars 
are connected with socket pipes. 

One rather important point in connection with the construction is that 
dealing with the proportions employed for the concrete. This is somewhat 
different from the usual mixture, it being composed of one part of Portland 
cement, one part of sand, and two parts of ballast for columns. The 
remainder is as follows : 1 cwt. cement, 2 cubic ft. sand, 4 cubic ft. ballast. 
It will be seen that the mixture for columns is much richer than that 
generally used, and in consequence a greater stress is allowed on the 
concrete per square inch, and a smaller quantity is used in consequence. 
It is claimed that economy is effected in this way, as the reduction 
in the quantity of concrete obviously reduces the loads to be carried 
and thus the sizes of the members are reduced throughout. The floor 
loads have been calculated at 3 cwts. per sq. ft. for the ground floor ot the ware- 
house and 2A cwts. for the upper floors, while in the offices the allowance is 
too lb. per sq. ft. for all doors and 65 lb. tor the roofs. These loads are in 
addition to the weight of the floor itself, and the slabs are only 3.' in. thick 
in the warehouse and ;; in. thick in the offices. These floor slabs are carried by 
secondary beams, which are in turn carried by main beams; and the whole ol 
the skeleton reinforcement, wherever possible, is built up complel h 
being placed in the moulds, as this is considered to be cheaper than 1 
up in the moulds and, furthermore, ensures mon accuracy in 1 1 
the rods. The external walls generally are 4 in. and 6 in. thi 

1 1 



H.M. NEW STATIONERY OFFICE. 



ro5CRKf£i 



of the office block facing- Waterloo Road will be faced with Portland stone, 
carried by the reinforced concrete columns and beams mainly at the level of the 
sub-ground floor. The chimney from the boiler-house is being- formed in rein- 
forced concrete, and this is no feet in height, with an inside size of 4 ft. ^, in. 
square, the sides being 7 in. thick at the bottom and 5 in. thick at the top. A 
fire-brick lining will be built in sections inside the shaft and supported by 
corbelling, this being kept 3 in. clear from the concrete sides. It is estimated 
that over 1,200 tons of steel will be required for the complete building, and as all 




Fig. 6. View showing Reinforced Concrete Work. 
H.M. New Stationery Office. 



this is in the form of small round rods, it represents a very large amount. The 
work is being executed by Messrs. Perry & Co., Ltd., of Bow, while the steel- 
work for the gantry was supplied and erected by Messrs. Drew-Bear, Perks 
& Co., Ltd., Battersea Street Works. The reinforcing- steel is being supplied 
by Messrs. Donnan & Long, of Middlesbrough, and the ballast is being pro- 
cured from the Ham River Grit Co., Rochester. 



SPECIFIC GRAVITY OF PORTLAND L 




THE 

SPECIFIC GRAVITY 

OF PORTLAND 

CEMENT. 



By PERCY C. H. WEST. 



The folloiving article may be of interest as indicative of some of the more recent m>3rk 
■which has been done in this particular branch of research.— ED. 




So much has already been written relative to the specific gravity of Portland 
cement, that a certain hesitancy is felt in reverting- to the subject. Much 
work has recently been done which is of merely confirmatory nature, and 
older and often more complete work has been overlooked; the results obtained 
by the several investigators have not been compared nor received adequate 
attention, with the natural result that in many quarters great importance is 
attached to the test, although the results of systematic research show that 
it is of extremely limited value. 

Nearly thirty years ago sufficient evidence had been collected to show 
that the test as an indication of the quality of cement was of little use ; in 
fact, could be well dispensed with. Yet to-day, as every manufacturer knows, 
there are many users of Portland cement who regard the test as of the greatest 
value, and who will disregard the more practical indications of high quality, 
such as mechanical tests and soundness tests, if the specific gravity falls below 
some arbitrary limit. The volume weight test to which the determination of 
specific gravity may be regarded as the natural successor has fallen — quite 
rightly — into desuetude. It was early recognised, notably by Grant, that the 
weight per bushel was a function of the state of division and the specific gravity, 
the method of carrying out the test remaining the same. 

As is generally known, the test was held to be of use in differentiating 
between cements which had been burned at a high temperature or clinkered 
and those burned at a lower temperature, as, for example, Roman cement. 
It will usually be found that Roman, or natural cement, which has not been 
clinkered has a lower specific gravity than Portland cement, but the mechanical 
strength tests will equally well enable the two classes to be differentiated. 
When the test is applied to Portland cement, with the object of ascertaining 
its quality or the degree of clinkering, the results are much less positive. 

Michaelis, in the earliest standard text-book on the subject, gives the 
specific gravity of Portland cement as $2, and states that the specific gravity 
of light burnt cement is not more than o'i lower and of overburnt 0*3 bel< 
this figure. 

Seger and Aron determined the specific gravity of a numb 
of Portland cement, and found that they gave figures varying 1 



» 5 



PERCY C. H. WEST. [ CPNCRETEJ 

and 3'° iS - Schumann (1883) determined the specific gravity ol twenty samples., 
and found that, as a rule, they fell between 3T10 and V 1 74 ; in one case he 
found over 3*23, but never obtained a figure below 3*1. These results indicate 
a considerable variation. The cause of this variation was only imperfectly 
known at the time. Erdmenger found that the specific gravity of a clinker 
was dependent on the temperature at which it was calcined. He found that, 
not only did underburnt cement have a low specific gravity, but clinker produced 
at a high temperature also gave a low figure. This fall in specific gravity is 
shown to occur as a result of burning at a very high temperature by the results 
of Fresenius, published in 1SS5. In this case the amount of carbon dioxide 
and of water present in the clinker was also determined. Vicat, in his book, 
" Cimente et Chaux Hydrauliques " (1891), states that the specific gravity 
indicates adulteration and degree of burning. In the figures given by him 
as an example, the same fall of specific gravity, as the result of clinkering at 
a high temperature, is indicated. 

Meyer, at a later date — 1S97 — obtained preciselv similar results, employing 
a mixture which, when burnt, had the following composition : — 

Composition; CaO + MgO CaO S1O2 ^Os 
66'6 64'25 32*4 

Cone ... 7 8 10 12 14 16 

S.G. ... 3-155 3'224 3'212 3 - 198 3i85 3*170 

These figures are of great interest, as they show the relation between 
the specific gravity and the temperature of burning the clinker with a greater 
degree of precision. As late as 1907 we find results of a somewhat similar 
character being published by Meade and Hawke. 

In view of the requirements of the specification of the Association of 
American Portland Cement Manufacturers, these chemists considered it 
necessary to emphasise the slight difference in specific gravity between 
imperfectly burnr and well-burnt clinker. They give examples showing that 
in a certain case the difference was onlv C026 : — 

1. Very light burnt .. ... ... 3'2oS 

2. Somewhat lightly burnt ... ... ... X 222 

3. Well burnt ... ... ... ... 3'- J 4 

4. Very hard burnt ... ... ... ... 3' -34 

In this case the clinkers were all produced from the same batch of raw- 
material, and were produced in the same rotary kiln. They further state that 
in no case have they found half-burnt giving a lower specific gravity than 3' 10. 

Butler (1906) found that, of thirteen samples of underburnt, eight possessed 
a sufficiently high specific gravity to satisfy the requirements of the B.S.S. 

Within the writer's experience the lowest specific gravity of a thoroughly 
clinkered mixture was 3-024. This clinker had an abnormal composition, 
containing only 50 per cent, of lime, and naturally disintegrated on cooling. 
With a normal composition the specific gravity of clinker produced from the 
same materials did not fall below 3' 17. 

From these results it follows that the sjx< itic gravity of a thoroughly well- 
burnt clinker varies between wide limits; that under certain conditions a large 

•4 



AENoiNtEBiNo^! SPECIFIC GRAVITY OF PORTLAND CEME 



-KN0INKKK1NG — J 



proportion ol material of lower specific gravity could bi added withou 

the- resultanl mixture to have a specific gravity less than many undoubtedly 

pure clinkers possess. 

Unreliable, however, as is the specific gravity lest when employed for 
estimating the degree of burning or the purity of ground clinker, ii is much 
more so as applied to finished cement. 

It is permissible to add a certain percentage of gypsum, a material having 
a specific gravity of 2'$ — 2'g. Fuel dust may be present in a cement, whereas 
in testing clinker its presence may be avoided. Water and carbon dioxide 
are absorbed by the cement during the grinding process, and in storing either, 
or both, may be intentionally introduced into the cement. Thus there are 
three additional factors which have an effect on the specific gravity of the 
cement. The first two may be neglected, as they are present in only small 
percentages, and their effect is therefore small. The latter, however, is of 
considerable effect, a fact observed at a very early date by Erdmenger, who 
found that a cement having a specific gravity of X 2 on storing five months 
absorbed r8 per cent, of water and C0 2 ; the specific gravity falling to 3'oo. 
After storing eight months r 2 per cent, had been absorbed and the specific 
gravity fell to 2'c/>. In another case quoted by him a cement having originally a 
specific gravity of 3'og after one year had absorbed 21 per cent, and its specific 
gravity had fallen to 2 "85. 

Schott (1885), recognising the cause of the decrease in specific gravity, 
suggested a method of calculating the specific gravity of the clinker from that 
of the cement. He found that a sample giving a loss on ignition of ^ per cent. 
had a specific gravity of 3'o94. Assuming the specific gravity of the clinker to 
be 3' 1 5, he calculates the specific gravity, if all the loss on ignition be due to 
water, as follows : — 

Specific Gravity of Water i"o 
97 + 3'15 + 3-00 + rOO = ..._- 
100 

If loss on ignition is due to C0 2 : 6'8CaCO 3 of S.G. 2 m y 

93 , 2 + 3'15 + 6'8 + 27 _ 3 . n 
100 

Assuming the cement to contain equal proportions of water and carbonic 
anhydride, we get the following S.G. : — 

3'085 + 3 , l l_ 3 . 0Q 
2 

Schott's equation may be put in the following form : — 

r _ 100y (n l)-(m 1'82) 
97 
where x is the specific gravity of the clinker ; y the specific gravity of the cement ; 
n = percentage of water; m = percentage of CO,. 

Hauenschild has suggested a purely empirical formula : 

Sb = Sa + S "- b 
100 



PERCY C. H. WEST. [CONCRETE! 

In which Sb = S.G. clinker. 

Sa = S G. unignited cement. 
b = loss on ignition. 
And F. M. Meyer has suggested Sb = Sa+ 0035b. 

These two formula? have been checked by Gary (1905) against actual deter- 
minations. As might be anticipated, the results are by no means concordant. 
It may be noted that the nineteen cements tested by Gary gave an average 
difference of 0^0445 per 10 per cent, loss on ignition. 

Butler has developed a formula enabling the specific of the clinker to be 
calculated from the specific gravity of the cement, and the percentage of water 
and carbon dioxide present in it being known. The calculation is, however, a 
somewhat lengthy process, and as the determination of the relative amounts of 
carbon dioxide and of water are necessitated, it is of little value. Another 
writer has suggested the calculation of the specific gravity of the clinker in a 
similar manner and has fallen into the error of taking the specific gravity of 
a compound to be the mean of the specific gravities of its constituents. That it 
cannot be done in the case of a lime-water reaction is apparent from the swell- 
ing up of lime on hydration and also from determinations of the specific gravity 
of calcium oxide and of the hydroxide. 

It has been shown by Brugelman, Moissan, Richter, and others that lime 
can be obtained having a specific gravity as low as 3'o8, or as high as 3*4, 
depending on the temperature at which it is burnt. The hydroxide in the 
amorphous form has a specific gravity of 2-078 (Rose) and crystallised in the 
hexagonal form 2-239- 2-241. If the specific gravity agreed with the simple 
rule of averages and the specific gravity of calcium oxide was yo, then that of 
the hvdroxide would be 2^, and if the oxide was 3*2 then that of the hydroxide 
would be 2 '66. 

As the specific gravity of clinker varies between such wide limits, and as 
the specific gravity of calcium hydroxide in its several forms is also variable, 
it is of little use calculating the fall in the specific gravity of clinker due to 
the absorption of carbon dioxide and of water. The following figures, however, 
indicate the possible effect : — ■ 

Reduction of S.G. by 1% HO 

0'033 
0-047 
0-013 by 1% CO, 

Of less moment in this connection is the addition of gypsum, the specific 
gravity of which, as CaSO t 2H -.O , is 2-306 Dumas, 2-331 Filhol. In the 
anhydrous form it has a specific gravity of 2.97 Schrauf. 

Calculations, therefore, arc of little value, as these results are mere approxi- 
mation-- .it best. The apparent alternative of driving off tin- moisture and carbon 
dioxide leads to little better results, but in view of iu relative simplicity it is t > 
be preferred to the other method. It has been well pointed out by Kupffender 
that by heating the cement to 110 — 120 only hygroscopic moisture is driven 
off. At higher temperatures first the combined water from the gypsum, then 

16 



Clinker S.G. 


~ r CaCO?. or 
5,a - CaiOH) 2 




assumed 


3-18 


2-24 


3"18 


2'08 


3-18 (CaCOj) 


2'7 



[&^JNEsSr%£9 SPECIFIC GRAVITY OF PORTLAND CEME 

from the calcium hydroxide, and finally the CO 2 from I he carbonates is expelled. 
Even then the mass does nol necessarily give the specific gravity of the clin 
for, as previously mentioned, the specific gravity of lime increases by heating. 
Only i! the cement is heated to the original clinkering temperature would an 
approximately correcl result be reached. And, if the heating was carried to this 
degree, 1400 - 1500° C, any badly burned or unburned material would be 
converted into material of high specific gravity. 

The determination of the specific gravity on cement as delivered is of no 
practical value, for if ii is desired to discover whether the cement has been 
Stored carelessly or too longj a determination of the loss of ignition will show 
it directly, and with a greater degree of accuracy. With regard to this point, 
too, an odd one or two per cent, is of little consequence if the mechanical tests 
prove that the cement has ample strength. Determination of the specific- gravity 
on the cement heated to redness gives more information than the test carried out 
on the unignited cement and may serve to indicate gross adulteration, that is if 
the lost free cement has a specific gravity less than 31. 

Nothing has yet been said with regard to the accuracy with which deter- 
minations of specific gravity are made. Differences between authorities is fairly 
common, but the following is an illuminating instance. Dr. Heiser took 

25 samples of cement, tested them himself, and had them tested at Gross Lichter- 
feld and at Mal'mes (Belgian State Laboratory), with the following average 
results : — 

Gross Lichterfeld. Malines. Dr. Heiser. 

3-150 3-118 3-127 

The greatest difference was 0076, while the average was o"o^_\ 

In conclusion, the words of Zwick (1879) m;i . v be well repeated : " It there- 
fore follows that the specific gravity is a doubtful criterion of the value of 
cement. " 



17 



T. D. KEY. 



ICQNCEKTFJ 








RECENT REINFORCED 
CONCRETE CONSTRUO 
TION IN ALEXANDRIA. 



3^Js*»^ 



By T. D. KEY 

(Alexandria Water Co., Ltd.) 

A considerable amount of •very interesting reinforced concrete "work has recently 
been carried out in Alexandria, and the following article deals ivith a few of these 
structures. —ED. 

To the well-informed mind the word Egypt generally conveys an impression of 
the Arabian Nights and romantic associations of a desert life, and the visitor 
in quest of such usually obtains something very much in the nature of a shock 
when his port of debarkation on Egyptian soil happens to be Alexandria. 

It would, indeed, be hard to find a greater contrast between the ideals of 
the first and the realities of the second than are presented by the town of 
Alexandria of to-day, and the tourist, realising this at sight, soon shakes the 
dust off his feet and departs for the more congenial delights of Cairo, Luxor, 
or Assouan. 

Yet to the observant mind Alexandria presents many features of interest, 
its commercial and industrial activity, together with a magnificent harbour, 
having made it again one of the foremost cities of the East, and in the process 
the enterprise of its citizens has neglected few of the advances in science and 
engineering which have helped to promote the success of its Western rivals. 

As the title of this article suggests, its object is to confine itself to giving 
a brief outline of the work done in Alexandria in those most recent methods of 
constructional engineering, reinforced concrete. And I think I am cornet in 
stating that the first reinforced concrete work of any magnitude carried out in 
that town was in 1905, when, during the reconstruction of the Water Works, 
the new clear water storage reservoirs were roofed over with this material. 
Constructionally these roofs present no features worth recording. One point, 
however, which may Interest your readers is the fact that, owing to a shortage 
of material, a considerable part of one of the roofs was made with concrete 
having as an aggregate ordinary furnace asli drawn from the Water Works 
boiler furnaces. About two years ago I had occasion to cut through the whole 
length of thai part of the roof so constructed, and no evidence of corrosion was 
noticeable on any part of the reinforcement. 

Since thai date the Water Works have carried out two important struc- 
tures in this material, the first, in 1900, a culvert connecting the company's 
private canal with the suction wells situated outside the main pumping house, 
iis object being to supplement an existing culvert in brickwork, built about 
forty years ago, and of whose safety the Water Works authorities had grave 
doubts. Before work was commenced on the culvert a new intake house was 
18 



I 



CCTMyrBucmaNAi.l 
emowe£rinu— J 



REINFORCED CONCRETE IN ALEXANDRIA. 




'**'* 



Fig. 1. Section. 
Reinforced Concrete Culvert. 
C 2 



built at the canal end, and ti 
both old and new culverts wen: 
finally connected. The control pen- 
stocks and screens were also placed 

in this house. 

The new culvert was made 
entirely of reinforced concrete and 
has a section as shown in Fig. i , 
this section being- determined on t he- 
assumption that it would be n< i es- 
sary to supply iyz million gallons 
(60,000 cubic metres) to the pumps 
in 12 hours when the water level in 
the canal was at a minimum of 3 ft, 
above the culvert invert. 

The reinforcing throughout was 
done by means of expanded metal, 
No. 10 size, having strands of 3-in. 
mesh, the section of the strand being 
•ns in. by ± i n ., the metal being laid 
the long way of the mesh at right 
angles to the axis of the culvert. The 
wooden centering used is well shown 
in the illustration, Fig. 2, and was 
made in lengths of 4 metres, each 
length being collapsible and easily 
removed alter the concrete had set. 
This centering was covered at each 
stage with oiled paper, thus pro- 
tecting the centering from deteriora- 
tion through contact with the con- 
crete, and also to provide a smooth 
inner surface to the culvert. So 
satisfactory were the results in this 
latter respect that in only a few 
places was it necessary to add an) 
cement rendering to the inner sur- 
face of the finished work. The fol- 
lowing mixture was used in making 
the concrete : 1 part of Portland 
cement to 3 parts of sand, 2 parts of 
this mortar to 3 parts of an ag{ 
gate composed of broken pottery 
thoroughly washed and screened 
through a 2-in. ring, all parts 
being measured by volume. 
Regarding the aggn word 

'9 



T. D. KEY. 



[CONCRETE ] 



of explanation may not be amiss. This is broken Egyptian pottery, 

known locally by the name "chakf." and immense quantities of this 
material are to be found all over Egypt buried under small hills, or " koms." 
Being- strong under compression, and having sharp edges, it makes a good 
aggregate for concrete when care is taken to use sufficient cement and sand to 
fill all the interstices. A disadvantage to its use in reinforced concrete, how- 
ever, is that it cannot be conveniently broken to a small size. This fact, 
together with the increased cost due to the available supplies around Alexandria 
being nearly exhausted, has practically stopped its use for this purpose. The 
concrete was mixed wet and well tamped into place, the outside shuttering 




Fig. 2. Wooden Centering. 
Reinforced Conxrete Culvert. 



being placed in position in narrow strips to enable this to be conveniently 
done. 

The culvert is provided with manholes about 262 ft. apart, these man- 
holes being formed in the crown of the arch, which is strengthened at these 
points by means of an angle iron saddle cast into the concrete. The depth of the 
crown of the arch below the surface level varies from 12 ft. at the canal end to 
24 ft. at the suction wells. At the deeper levels reinforcement was placed on 
the outer side of the crown in order to provide against the increased horizontal 
thrust. The total length of the culvert is about 1,670 ft. 

The second ; s a settling basin, forming one of a group of four, and used lor 
precipitating, under the action of alumina sulphate, the tine Nile mud held in 
suspension in the water before this is treated by the filters. 

Its construction is well shown in the drawing. Fig. 3, and its action as an 

20 



g 



. OONSTPIJCTIONAL 
ENGINEERING — . 



REINFORCED CONCRETE IN ALEXANDRIA. 



efficienl precipitating tank may be briefly described thus 



y. 





which this settling tank was 



be constructed was of 



The unfiltered 

is pumped inl i 
the semi-circular 

basin, A, from 

which it flows 

with a greatly 

d i m i n i s h e d 

velocity towards 

t li e diaphragm 

wall at I}. This 

diaphragm i s 

composed of two 

parallel w alls, 

that nearesl the 

inlet acting as a 

weir, the other 

as a baffle with 

opening's at its 

glower base 

h through w h i c h 

S the water passes 

t to the outlet over- 

$ flow weir at C. 

u These two weirs 

z have the effect oi 

^ skimming off the 

o 

g surface and 

2 (dearer water in 

3 each compartment 

Si ' 

of the tank, and 
retain the greater 
quantity oi silt 
left in suspension 
in the lower water 
levels. The work- 
ing capacity of 
the tank is one 
million gallons 

and the t i m e 
allowed for this 
quantity to flow 
through is i 
lated to about six 
hours. 

• 
g r o u n ci 
a nature which 



T. D. KEY. 



[QQNCKETE3 



precluded any hope of obtaining a uniform foundation, it was decided 
to flood the whole surface until such time as all voids had been filled and 
infiltration ceased, and for this purpose one of the unfiltered water-pumps 
was utilised during" fifteen days, pumping altogether about 8,000,000 gallons 
before this result was obtained. 

On the ground drying off, a 20-ton steam roller was run on the land, and 

rolling continued until the surface was brought to a uniform level and no further 

1 




Fig. 4. Details of Reinforcement. 
Ri inforced Concrete Settling Tank. 

settlement visible when the roller was at work. An examination of the land 
after this proved so satisfactory that it was decided to dispense with anything 
further in the way of foundations, and work was at once commenced in excavat- 
ing the surface to the exact camber of the tank bottom, and on this a dry course 
of broken stone was rammed, sufficient only to form a clean surface on which lo 
lay the reinforced concrete. 

The design adopted shows remarkably well the economj of material to be 

22 



foco^rutjcnasAii REINFORCED CONCRETE IN ALEXANDRIA. 

obtained from the use of reinforced concrete for this class of work. The bol 




— u 
z 
o 
U 



«r 



of the tank is a continuous slab, 4 in. thick, reinforced longi 



T. I). KEY. 



(CONCBETEJ 



transversely by |-in. rods pitched 8 in. centre to centre each way. The side 




Figs. 6 iV 7. In Course of Construction. 
Ki inforced Concrete Cotton Stori s, 



walls are 
2 4 



5i m - thick at the base, tapering to 4 in. at the top, and supported 



s 



, CONSTBUCTIONA 1.1 
LNf.lNfcLKING — J 



REINFORCED CONCRETE IN ALEXANDRL 



throughout their length by buttresses pitched n ft. 6 in. centre to centre. 
4-ft. platform runs round the tank- for inspection purposes, and in the manner 
of its attachment to the side walls and buttresses advantage is taken of its 
position to render that pari of the side wall contained between the buttressi 

a slab supported on all four sides, thus keeping these at a minimum for thii kness 
and reinforcement. Details of the reinforcement in the buttresses and its attach- 
ment to the rest of the tank are given in Fig. 4. This also shows the beam 
placed on the inner side of the side wall and under the bottom slab to take the 
negative bending- moment, due to the weight of the side walls, when the tank is 
emptied for cleaning purposes. 

The composition of the concrete throughout the entire work was made in 
the following proportions : 1 cubic metre of gravel screened through a f-in. 




Fig. 8. 
Reinforced Concrete Pontoon Breakwater. 



ring, i cubic metre of sand, and 350 kilos, of cement, the whole being mixed by 
hand, then watered and mixed to a wet concrete. 

In order to prevent infiltration the bottom of the tank was covered by a 
continuous sheet of Aqualite Bitumen Sheeting, over which was laid a protecting 
layer of concrete 2 in. thick, the side walls being rendered with a 2 to 1 cement 
mortar worked to a finished surface. As regards the side walls, it is interesting 
to note that the results obtained have been perfectly dry outer surfaces, and 
this result is the more remarkable when taken into consideration with the 
extreme ranges of temperature to which these exposed walls are daily < 

The aforementioned works have all been designed and executed 
direction of Mr. H. R. C. Blagden, M.I.M.K., the Central Manag 
Alexandria Water Company, Ltd. 

2 5 



T. D. KEY. 



[CONCRETE! 



Another use for which reinforced concrete is finding- increased favour in 
Alexandria is in the construction of cotton stores, or " chounahs " as they are 
locally called. These chounahs are of immense size, and in view of the 
exceedingly valuable nature of their contents (manv chounahs have cotton 
stored to the extent of over half a million sterling- during the busy season) one 
of the essential points in their construction is fire-resisting qualities. The most 
recent practice in building these is to construct a skeleton work consisting of 
reinforced concrete columns pitched longitudinally and transversely at equal 
distances, these columns supporting the floors and roofs, which are made of 
the same material. The outside walls are of siliceous sand bricks, laid as panels 

between the columns, the 
interior division of the 
chounah into separate com- 
partments being provided 
for in a similar manner. 

Although from the 
aesthetic point of view these 
buildings leave much to be 
desired, yet for strength, 
low cost of upkeep, and 
immunity from fire risks 
they are an immense im- 
provement over those 
chounahs constructed at an 
■pP^^tJ -VJ= ^5~ V ~' earlier date, and wherein 

the floors, roofs, and 
columns are in woodwork. 

In the harbour several 
notable works in rein- 
forced concrete have been 
carried out under the direction of Monsieur Jondet, the Chief Engineer of the' 
Port. These include a small breakwater built in pontoon form on land, 
launched, towed into position, and sunk. Latterly the same engineer has been 
responsible for the construction of a lighthouse on the same principle. The light- 
house in question marks the entrance to the main channel and replaces a steel 
structure destroyed during the winter storms. After the site had been carefullv 
levelled by divers the base or foundation of the structure, which was built as a 
monolith and in the form of an octagonal cone, was launched and floated into 
position, and after this was sunk and ballasted the superstructure or lighthouse 
proper was added /'// situ. 




Fig. 9. 
Launching Pontoon Breakwater. 



26 



r a r CONSTBUCTIOMALS 
I ft. UNGIMeLrING— 'J 




PRACTICAL DESIGN OF FLAT SLAJsS. 



THE PRACTICAL DESIGN OF 

REINFORCED CONCRETE 

FLAT SLABS. 



J 



By SANFORD E. THOMPSON* 

The following paper ioas presented at the meeting of the National Association of Cement 
Users, U.S.A., in March, 1912, and as the designing of Flat Slabs for Reinforced Concrete 
Work is one claiming considerable attention, iue have reprinted the paper here to show some 
of the views held on the subject in the United States. — ED. 



The purpose of this paper is to present material covering the practical task of design- 
ing flat slab floors for reinforced concrete structures. The requisite thickness of slab, 
amount of reinforcement, and size of column head, for different loadings and different 
spans, are given in a table; and the theories and assumptions involved in the com- 
putation are briefly discussed. Values not included in the table may be worked out 
from the formula, finding the desired values of C 5 and C from the diagrams. t 
Curves are given also for the constants used in the design of members with steel in 
top and bottom, and apply not only to flat slabs, but to any beam or slab reinforced 
both in compression and tension. 

For reinforced concrete buildings, the flat slab — or girderless floor, as it is some- 
times called — is as cheap, and frequently cheaper, than beam and girder construction. 
The smooth ceilings with no intersecting beams allow better distribution of the light. 
The expense and complication of installing sprinkler systems are lessened. The clear 
headroom for the same story height is increased, or else, on the other hand, the story 
height may be made less without reducing the effective headroom. This last vud- 
sideration alone is often important enough to dictate flat slab floors. 

With flat slab floors the entire load is supported directly on the columns, which 
are usually spaced about equally in both directions. The column heads are enlarged 
so as to give increased resistance in shear and bending at the points where this is most 
needed. The reinforcing bars run through the slabs over the column heads in four 
directions, two rectangular and two diagonal. 

The simplest wav of considering the flat slab is to assume that ,a portion of the 
slab extending a certain distance out from the column is a flat, circular plate, similar 
to a Japanese parasol, but with no slope to its surface. This plate is fixed to the 
column and is assumed to extend out from it on all sides like a cantilever as far as 
the line of inflection of the slab, which line — as in other forms of monolithic construc- 
tion — is about one-fifth of the net span away from the support. The rest of the slab 
may be considered as entirely separate from the flat circular plates, hut simply supported 
from their outer edges or circumferences. 

This is no new theory, hut is somewhat similar in effect to that of a uniformly 
loaded, fixed or continuous beam. To illustrate this in practical fashion, we will take 
an ordinary beam uniformly loaded and fixed at both ends. This illustration do< 
in any way show the methods of determining a bending moment in the flat slab, sL 

* Consulting Engineer, Newton Highlands, Ma«., U.S.A. 

t For an example of flat slab design worked out in detail set Taylor ami I 
Plain and Reinforced," 2nd edition, 1911, pages 4S7 and 488. 

27 



SAN FORD E. THOMPSON. [(X?NCREfB 

as stated below, the actual bending moment is dependent upon the elastic theory. It 
does, however, show quite clearly that we are justified in assuming the slab to be : ul 
through on the line of inflection. 

We know from simple mechanics that the moment at the support of an ordinary 
uniformly loaded fixed or continuous beam is Wl/12* and, at the centre, is 117 24. 
Now, suppose at the points of inflection, which also by mechanics we know to be 
located at a distance 0-2113/ from each support, we cut the beam completely through 
so a.s to have a cantilever at each end with a simply supported beam between. The 
bending moment of the cantilever at its support, due to the load upon it, is 
o'2i 13 H' x o - 2i 13/ 2, and the moment at its support due to the load on the supported 

T ^lO' ' I I ^) 

beam between cantilevers, is— Wx n':ii^I. The sum of these two moments 

2 

is 0*0223 117 + o'o6io 117 = (i-oS33 117 or 117 12. In other words, while this analysis is 
not that which can be used for a flat slab, because of the extra strength of the flat slab 
due to the multiple reinforcement, the division into sections corresponds to our assump- 
tion in the flat slab theory. In the same way we might show that the centre moment 
of the simple beam supported by the two ordinary cantilever beams is TIT/24. 

Tests of the flat slab construction at Minneapolis* indicate that the line of inflection 
of a flat slab floor is substantially the same as in a fix<d beam, or about 1-5 the net 
distance between supports, although, as would be expected, the bending moment is 
entirely different. 

PROBLEM OF DESIGN. 

The problem of the design of the flat slab, then, resolves itself into (i\ a determina- 
tion of the proper thickness and reinforcement required at the support for the cantilever 
circular plate supporting its own load and also the load of the rest of the slab, and 
(2) a determination of the thickness and reinforcement at the centre of the span required 
for the simply support d section lying between the circular plates. 

Various Methods of Design of Slab. — Various methods have been advanced for 
the design of the flat slab. Some are based merely on deflection tests, which give no 
true basis for computations; others compute the steel carefully at the centre of the slab, 
which is not the critical part ; others consider the construction to consist of beams 
between columns with a slab between, thus obtaining ultra-conservative results; while 
a plan still more common is to take the moment at the supports arbitrarily without 
regard to the size of the column head. The shear or diagonal tension near the column 
head is frequently disregarded altogether. 

Shear at the Support. — The direct shear at the support, as in any mechanical 
construction, is equivalent to the total load supported by the column. This shear is 
readily borne by the concrete aivl steel. The diagonal tension, however, which, as in 
a beam, may be considered as measured by direct shear, must be carefully considered. 
I>i reduce the diagonal tension and also to increase the resistance to bending of the 
slab, the column head is enlarged. To still further increase the resistance, a part of 
the bars in the top of the slab over the supports may be bent down just outside of the 
supports and then carried along in the bottom of the slab. 

In either case, the shearing stress should 1m- limited to definite units, although it 
seems permissible to use a somewhat higher stress than in a beam. 

The diameter of the enlarged column head, which is the actual support of the slab, 
should be governed by the shearing stress either at its circumference or at a short 
distance outside of it. 



* W = total live plus dead load. /= distance in feet between supports. 

t Sei papei \ [\ >( "i a Flat Mai. Floor in a Reinforced Concrete Building," by Arthur K. 

Lord, Proceedings National Association «/ Cement Users Vol V 1 1 . page 156. 

28 



f».coi<k1WKflWUIJ 



PRACTICAL DESIGN OF FLAT SLABS. 



Bending Moment at Support. — The theory of flai plates, which must b( used in 
designing a circular plate, is not yet clearly established. By the use of what is ta 
in mechanics, the elastic theory, we haw a fairly good working hypothesis. The 
analysis solved by Prof. II. T. Eddy* offers, in the writer's judgment, the most rational 
solution of the problem yet advanced. 

In the design of the flat slab, therefore, the author 1 - has started with Prof. Edd< '- 
analysis of stresses in a homogeneous circular plate, and from his general formulas 
has deduced by mathematics other formulas applying to circular plates free on their 
edges and clamped around the columns. In a Hat slab thus supported there are 




I' .Theoretical line \ 
A- of inflection \ 
Assumed line 
^ of inflection 



W in pounds per square foot 

M I I II 







1 pounds per linear foot 



Figs. 1 & 2. Plan and Section of Flat Slab. 



horizontal stresses at right angles to each other. The effect of these lateral stresses 
has been taken into account, this being expressed by Poisson's ratio, which is the ratio 
of the lateral deformation to the deformation in the direction of the stress. The value 
of this ratio is taken as p'l, which has been shown by experiments to be a fair val 
for concrete of 1:2:4 proportions. 

It has been found possible to reduce the complicated formulas derived by 1 



* Engineers' Society, University of Michigan, 1899. 

t The author is indebted to Mr. Edward Smulski foi the computati. ing intr: 

by higher mathematics; al-o to Mr. John Aver for further studies in the practical c 

29 



SAN FORD E. THOMPSON. iOQNCREXEj 

analysis into four formulas which are comparatively simple although still rather com- 
plicated for practical use. These formulas are for four bending moments and can be 
applied not merely to the slab at the support, but to any point in the circular plate 
surrounding the column. The four moments are as follows : 
3/i= moment produced by the loading that is uniformly distributed over the circular 

plate and causes circumferential fibre stress. 
M-,= moment produced by this same loading, but which causes radial fibre stress. 
M = moment produced by the loading from the rest of the slab that is distributed along 

the outer edge of plate, and causes circumferential fibre stress. 
M h — moment produced by the latter loading, but which causes radial fibre stress. 

A study of the analysis, however, shows that the two circumferential moments are 
a minimum at the support and may be safely disregarded. The two formulas for the 
radial moment may be combined and still further reduced to the following simple form 
which can be used for a circle of any radius, r, within the circular plate. The meaning 
of the symbols is made clearer by reference to Figs. 1 and 2, which show the plan and 
the section of a flat slab. 

Let 
q = uniformly distributed load around the outer edge of the plate in pounds per foot of 

length. 
iu = uniformly distributed load on surface of plate in pounds per sq. ft. 
f =radius in feet to line of maximum bending moment (which is within the column 

head). 
y x = outer radius of assumed plate in feet. 
r = any radius in feet where moment is to be computed; for critical section, r is radius 

of column head. 
C-, C e = constants given in Figs. 3 and 4. 
M r = total radial bending moment to be used ordinarily. 
l x —distance in feet between lines of inflection. 

Then total radial moment at any point of plate is — 

M r = wr% C 5 + qr C e 

For convenience in computation, values of the constants C s and C e , for various 
values of the ratios r l /r f) and r/r , are plotted in the curves given in Figs. 3 and 4.* 

With </ expressed in pounds per foot of length, w in pounds per square foot, and 
r in feet, the moments are in foot-pounds per foot or inch-pounds per inch. 

Position of Maximum Bending Moment and of Maximum Stress. — As 
commonly constructed, the column head flares at the top and is therefore more or less 
flexible. For this reason the line of maximum bending moment will be located, not at 
the extreme edge of the column head, but a little within it. The maximum stress, on' 
the other hand, will not be on the line of the maximum bending moment because the 
strength there (since it is within the head) is increased due to the greater depth of 
concrete. It is fair to assume, therefore, that the maximum stress is at the edge of 
the column head, and we may assume the " critical section " as on this line. The exact 
location of the line of maximum moment is indeterminate. Under ordinary conditions 
it appears fair to assume its location as within the column head, a distance equal to 
the thickness of the slab. Therefore, M r \s figured for a value of r = r o +t. In figuring 
this moment, values of the constants C and C e should be taken from the curves in 
Figs. 3 and 4. As in an ordinary fixed beam, this bending moment is negative, so that 
the upper side of the slab is in tension and the lower in compression. Having found 
the moment, the design of the reinforcement and the thickness of the slab may be 
worked out as for an ordinary beam. 

The curves in Figs. 5 to 8 inclusive will be found of assistance in working out the 
design. 

Steel in Column fiead.i The slab at the column head might be designed with 
the steel all in the top of the slab running in four directions provided the slab is thick 

* These are drawn up from values in tables in Taylor and Thompson's " Concrete, Plain and Rein- 

2nd edition, 1911, pa 
I ( rtain feat I flat slab reinforcement are covered by Litters Patent, No. 1003384, of C. A. P. 

turner. 

3° 



f&^GSJEMiNG^ PRACTICAL DESIGN OF FLAT SLABS. 

enough so that the concrete will not 1m- overstressed in compression. In order to reduce 
the thickness of the slab, anil therefore save the additional cost and weight of con 
over the entire floor, it is economical to place steel in the bottom of the slab as well as 
the top, and figure it as assisting the concrete to take compression. Since a portion 
of the bars need to extend only far enough beyond the column head to furnish suitable 




«•■ «5 «3 w . °u 






2 a 



& ° 



2 5 = 



•— , _y io 



o ™ 



a o 



c«-- 



* § 5 

i- O S 

II II II 



. l-i 




-" ii 











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m 




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X! 






u 




■a 




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l 


x 


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<u 




r R 






o 


L) 


ja 








u|l! 




x 


E 






3 


O 

10 

4) 

3 

n 


< 
> 




u 


£ 

a) 
E 

O 


3. 

D 

i 


5° 

i.l 

u -a 
u a 

■j ■- 


rtl 


> 


U 


* 


P 


3 
/; 
Efl 

a! 


8? B 










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.ft o 






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II II 



4.UD4.SUOO ^0 sanjDA. 
bond, the cost of this additional steel will be much less than the cost of an additic 
thickness of concrete over the entire slab. 

To make it easy to place the concrete and also to bring the centre of gi 
steel as near to the surfaces of the slab as possible in order to give the longest 
arm and thus a thinner slab, two layers of steei max be placed in the top oi th 

31 



SANFORD E. THOMPSON. [CONCRETE 



and two layers in the bottom. The relation of the quantity in the top and bottom must 
be determined by the design. If a thin slab is desired, even more steel may be placed 
in the bottom than in the top. In the tables, three ratio-, of Med are given, and the 
percentages selected are those that will give the required working stresses in the 
concrete and the steel. 

The Minneapolis test already referred to shows that not only the steel directly over 
the column head, but the steel for a considerable distance each side, takes tension. 
In view of this test and of the tests made at the University of Illinois,* it is safe to 
assume that the steel may be spaced over a distance at least equal to the diameter of the 
column head plus three times the thickness of the slab. 

The determination as to whether the diagonal or rectangular steel should be placed 
at the top is governed bv the relative quantities of each. More steel is required for the 
diagonal direction through the slab, hence the layers which are largest in section may 
be run diagonally. 

Agreement with Minneapolis Tests. — By our theory it is possible to compute the 
stresses not only next to the column head, but at any point in the slab. In several 
cases, knowing the exact location of the points where the deformations were measured 
in the Minneapolis tests, we have computed the stresses at these points. Using 5-6 in. 
as the moment arm, and including the radial bars as assisting to take tension, we figure 
the maximum stress in the steel over the edge of the column as 25,000 lb. per sq. in. 
under the normal load of 22^ lb. per sq. ft., as compared with 20,700 lb. per sq. in. 
given bv Mr. Lord as the actual maximum stress in the floor. This is no greater 
difference than there ought to be between design and test, and shows our method to be 
slightlv more conservative than the actual test. 

The compression in the concrete is more difficult to check since the exact locations 
of the test points are not given. Computations, however, show unquestionably that 
our methods are conservative enough to allow for the irregularities in concrete mixtures 
and the danger of not having perfect concrete at the critical section. 

Moment at Centre of Slab. — It is possible to adapt the Eddy theory to the 
design of the centre of the slab as well as to the supports. In practical design, however, 
as has been indicated, the thickness of the slab is determined by the thickness at the 
support, which is always the greater. But, in order to avoid too wide spacing of the 
bars and to adapt the centre reinforcement to that over the supports, more steel is 
generally run through the slab than the results of tests would show to be necessary. 
Consequentlv, instead of considering this from a theoretical standpoint alone, safe 
values for the bending moments may be selected, based on general principles of 
mechanics and qualified by actual tesis. 

Let J, = distance between lines of inflection. This distance will be about three-fifths 
of the net span between column heads. 

For the rectangular reinforcement, if the slabs between the points of inflection 
were simply supported, we should have a moment of ;e/,'-/8. However, the bending 
moment in the Minneapolis tests, based on the maximum stresses under uniform 
working load, is about wl^ 33. It would appear amply safe, therefore, to adopt a 
value of M =wl , 2 /l2. 

For the diagonal reinforcement, the steel runs in two directions, and considering 
both theory and test, a value of M = wl 1 2 24 is conservative to use for the steel in each 
direction. 

Cross Steel Between Columns. — In fiat slab doors, cracks are apt to occur 
between columns on rectangular lines, because, since the span is shorter, the deflection 
is less than in the centre of the slab. To prevent these tracks, it is advisable to place 
cross reinforcement of small bars in the to]) of the slab. 



* See paper on "A Test <>i a Flat Slab Fl it in a Reinforced Concreti 
>rd, Proceedings National Association of Cement Users, Vol. VII., page 18a. 

3* 



& 



ENGJNEER1NG- 



PRACTICAL DESIGN OF FLAT SLABS. 



TABLES FOR DESIGN OF SLABS. 

The accompanying tables give thicknesses of slab, reinforcement, ;m<l size of column 
head, for various column spacimgs and loads. 



0.040r 




0.10 0.15 0.20 0.25 0.30 0.35 0,40 0/45 0.50 0.55 0.60 
Valuer of Constant C c 
a=O.I0 

0.040r 




0.10 0.15 0.20 0.25 0.30 0.35 0.40 0,4-5 0.50 0.55 0J60 
Valuer of Constant C c 
a- 0.15 

Fig. 5. Diagram Giving Values of Constants in Formula 
1/ 
f c = ■■- — for a = 0.10 and a =0.15 
C c bd- 



Depth of Steel in Tension. 



P = 



Area of Steel in Tension. 
Area of Concrete above Steel. 



Three arrangements for steel over the column head are chosen : 
the area of steel in the top is twice the area of steel in the bottom ; the 
o 



SANFORD E. THOMPSON. [CONCRETE , 

the two are equal; and the third where the area of steel in the bottom is ; one , and a 
half times that in the top. This gives the designer a variety of thtcknesses of slab. 1 he 




oWm^^^^J^^ + 0A * a5 ° a55 a6 ° 

Vcilues of Constant U= 



a-0.20 



0.040 
0.035 




o^oais^oa^oSoo^s Q40 o.45 o.so a55 o.so 

Values of Cons+ont C c 
a = 0.25 

Fig. 6. Diagram Giving Values of Constants in Formula 
f-=_^L for a =0.20 AND a =0.25 
C bd* 



D epth of Steel in Compression. 
I lepth of Steel in Tension. 



Area of Steel in Tension. 

' Area of Concrete above Steel. 



oeroenteges of steel selected are those which produce, with the given conditions a 
S^ES. stressof 800 lb. pe. sq. in. m the concrete and ^,000 lb. ,n .the sieel. in 

34 



1 



eONSTPUCTlONA Li 
ENCilTjEERl NO —J 



PRACTICAL DESIGN OF FLAT SLABS. 



order to allow 800 lb. in the concrete, it should be mixed in proportions as rich as one 
part cement to two parts fine aggregate to four parts coarse aggregate. Poisson's 
ratio is assumed as o'i, which from recent tests appears to be a fair value. 

The size of column head lias been figured for a shear of 60 lb. ner sq. in. on a 
circle a distance, t (the thickness of slab), outside of the column head. This shear is 
used simply as a measure of the diagonal tension. The value is somewhat larger than 
is permitted in beam design, but appears to be warranted in the case of tlai slabs. 

The steel in the centre of the slabs has been figured for a stress of 16,000 11). 

Diagrams for Designing Slabs.— To provide for cases not covered by the table, 
curves for values of C 6 and C e are given, so that the moment under various conditions 




0.10 0.15 0.20 0.25 Q.30 0.35 040 045 0.50 055 0.60 
v Values of Constant C c 

a = 0.30 

Fig. 7. Diagram Giving Values of Constants in Formula 
M 



f c = „ T FOR a =0.30 
C c bd- 



Depth of Steel in Compression. 
Depth of Steel in Tension. 



P = 



Area of Steel in Tension. 
Area of Concrete above Steel. 



can be readily figured from the formula for the bending moment given in a preceding 
paragraph. 

Diagrams for Determining Steel in Top and Bottom of Beams or Slabs.— 

In Figs. 5 to 8, curves are plotted for finding the values of the constants C c and C, in 
the formulas for the steel and concrete stresses in beams or slabs with steel in top 
and bottom. The curves are drawn for different values of o, the ratio of distance of 
steel in compression from compression surface to distance of steel in tension from 
compression surface, and for different values of p'/p. where £ = ratio of cross-section 
of steel in tension to concrete above it,* and />' = ratio of Gross-section <> : 
compression to this same area of concrete. 

* Where the tension steel is at the top, as over the support of a flat slab or beam, the 
is taken below the tension steel. 






SANFORD E. THOMPSON. 



(CONCRETE] 



TABLE I.— DESIGN OF FLAT SLABS. 
Thickness of Slab, Areas of Steel and Sizes of Column Head are Given for Different Spans and 

Percentages of Steel. 









L 


ive Load 100 lb. per sq. 


ft. 










Ratio 


Ratio 


Distance 










Minimum 


Minimum 




of cross- 


of cross- 


from 










area of 


area of 


Span 
between 


section of 


section of 


bottom 


Approxi- 


Diameter 


*Area of 


♦Area of 


steel 


steel 


steel in 


steel in 


of slab to 


mate total 


of column 


steel over 


steel over 


between 


between 


centres of 


tension 


compres- 


centre of 


depth 


head. 


column in 


column in 


columns 


1 1 1'linin- 


columns 


to 


sion to 


gravity of 


of slab. 






compres- 


per foot of 


per foot of 


in feet. 


concrete 


concrete 


steel in 








sion. 


width of 


width of 




below 


below stee! 


tension. 










diagonal 


rectangu- 




steel. 


in tension. 












band. 


lar band. 




iP) 


(M 


M 


M 












ft. 






in. 


in. 


ft. 


sq. ill. 


sq. in. 


sq. in. 


sq. in. 


12 


0-014 


0-007 


4t 


54 


2-00 


4-50 


2-25 


0-16 


0-09 


12 


0-017 


0-017 


3* 


5 


2-O0 


4-81 


4-81 


0-17 


0-09 


12 


0-022 


0-033 


Ji 


4i 


2-30 


7-26 


10-90 


0-18 


0-09 


14 


0-0I4 


0-007 


5 


61 


2-25 


5-94 


2-97 


0-19 


o-n 


14 


0-017 


0-017 


44 


5i 


2-75 


7-93 


7'93 


0-20 


o-n 


t4 


0-022 


0-033 


4 


5i 


3-00 


9-06 


14-95 


0-21 


o-ii 


16 


0-014 


0-007 


6 


74 


3-00 


9-51 


4-76 


0-22 


0-12 


16 


0-017 


0-017 


5r 


6J 


3-25 


10-95 


10-95 


0-23 


0-12 


16 


0-022 


0-033 


Ah 


5l 


3-75 


14-01 


21-05 


0-24 


0-12 


18 


0-014 


0-007 


6f 


81 


3-50 


12-48 


6-24 


0-26 


0-14 


18 


0-017 


0-017 


6 


7\ 


3-75 


14-42 


14-42 


0-27 


"I) 


18 


0-022 


0-033 


5 


61 


4-50 


18-67 


28-00 


0-28 


0-I4 


20 


0-014 


0-007 


7i 


91 


4-00 


16-36 


8-18 


0-30 


0-16 


20 


0-017 


0-017 


6i 


81 


4-50 


19-47 


19-47 


0-31 


0-16 


20 


0-022 


0-033 


5l 


71 


5-00 


23-89 


35-8o 


0-32 


0-15 


22 


0-014 


0-007 


Si 


ioi 


4'50 


20-21 


10-11 


o-34 


0-18 


22 


0-017 


0-017 


71 


9 


5-00 


24 - 05 


24-05 


o-34 


0-17 


22 


0-022 


0-033 


64 


8 


5-75 


.31-05 


46-60 


o-35 


o-i6 


24 


0-014 


0-007 


94 


»i 


5-00 


25-IO 


12-55 


0-38 


0-20 


24 


0-017 


0-017 


8 1 


10 


5-75 


30-4I 


30-41 


o-39 


0-20 


^4 


0-022 


0-033 




8* 


6-50 


37-80 


56-70 


0-40 


0-19 



* Area of steel over column head = circumference of column head in inches xdxp or p' depending upon whether 
the steel is in tension or compression. This steel is assumed as distributed over the entire widths of the bands. Thus 
if a band of steel has 2 sq. in. steel in section, the area, effective, for two bands will be 8 sq. in. (See example.) 

TABLE II.— DESIGN OF FLAT SLABS. 
Thickness of Slab, Areas of Steel and Sizes of Column Head are Givex'for Different Spans and 

Percentages of Steel. 
Live Load 150 lb. per sq. ft. 





Ratio 


Ratio 


Distance 










Minimum 


Minimum 




of cross- 


of cross- 


from 










area of 


area of 


Span 


section of 


section of 


bottom 


Approxi- 


Diameter 


*Area of 


*Area of 


steel 


steel 


between 


steel in 


steel in 


of slab to 


mate total 


of column 


steel over 


steel over 


between 


between 


centres of 


tension 


compres- 


centre of 


depth 


head. 


column in 


column in 


columns 


columns 


columns 


to 


sion to 


gravity of 


of slab. 




tension. 


compres- 


per foot of 


per foot of 


in feet. 


concrete 


concrete 


steel in 








sion. 


width of 


width of 




below 


below steel 


tension. 










diagonal 


rectangu- 




steel. 


in tension. 












band. 


lar band. 




(P) 


(P f ) 


w 


d) 












ft. 






in. 


in. 


ft. 


sq. in. 


sq. in. 


sq. in. 


sq. in. 


12 


0-014 


0-007 


4* 


6 


2-25 


5-64 


2-82 


0-18 


o-io 


12 


0-017 


0-017 


4i 


54 


2-50 


6-8i 


6-8 1 


0-19 


o-io 


12 


0-022 


0-033 


34 


4i 


3-00 


8-72 


13-09 


0-21 


O-IO 


14 


0-014 


0-007 


54 


7 


3-00 


8-72 


4-36 


0-22 


0-12 


14 


0-017 


0-017 


5 


61 


3-50 


11-22 


11-22 


0-23 


II- 1 1 


M 


0-022 


0-033 


4i 


54 


3-75 


I3-22 


I9-82 


0-24 


o-ii 


16 


0-0I4 


0-007 


64 


8 


3-50 


12-03 


6-02 


0-26 


0-14 


16 


0-017 


0-017 


5i 


71 


3-75 


13-83 


13-83 


0-27 


0-13 


16 


0-022 


0-033 


4l 


6 


4-50 


17-75 


26-60 


0-28 


0-13 


18 


0-OI4 


0-007 


71 


8| 


4-00 


I5-32 


7-66 


0-31 


o-i6 


18 


0-017 


0-017 


61 


7l 


4-50 


18-05 


18-05 


0-32 


0-15 


18 


0-022 


0-033 


51 


61 


5-5° 


24-00 


36-00 


0-33 


0-14 


20 


0-0I4 


0-007 


81 


10 


5-00 


21-80 


10-90 


o-34 


0-17 


20 


0-OI7 


0-017 


7 


84 


5-50 


24-70 


24-70 


o-35 


0-17 


20 


0-022 


0-033 


6 


74 


6-25 


31-14 


46-70 


0-36 


0-16 


22 


0-014 


0-007 


9 


1 of 


5-5o 


26-15 


13-08 


0-38 


0-18 


22 


0-0I7 


D-CU7 


7\ 


91 


6-25 


31-07 


31-07 


o-39 


..•17 


22 


0-022 


0-033 


6J 


81 


7-00 


39-24 


58-80 


0-40 


0-17 


24 


0-014 


0-007 


9i 


11J 


7-00 


36-05 


18-03 


0-42 


0-21 


24 


0016 


0013 


82 


104 


700 


3695 


2957 


0-43 


0-20 



The values printed in black type are figured for a column head 7 ft. in diameter, and the thickness of the slab is 
increased to withstand tin shear. If th<- reinforcing rods are so bent that more than 60 lbs. in shear can be allowed 
mi the concrete, the thickness of the slab may be decreased provided the steel areas are increased sufficiently to give 
the desired strength. 

•Area of steel over column head=circumference of column head in inches xi/x/> or />' depending upon whether 
th( Steel is in tension or compression. Thi» - 1 < •- 1 is assumed as distributed over tin- rutin widths of the bands. Thus 
if a band of steel has 2 sq. in. Steel in section, the area, effective, for two bands will be 8 sq. in. (See example.) 

36 



1 



^ C0N5Tk'UtT10NA 
ENG1MEEJJ1NC 



saE] 



PRACTICAL DESIGN OF FLAT SLABS. 



lAI'.l.K III.— DESIGN OF FLAT SLABS, 

Thickness of Slab, Arf.as of Stf.f.l and Sizes of Column Hi ad ARE I .in N pi >R DIFFER] .r Spans and 

Percentages of Steel. 
Live l.o.ul 200 Hi. per sq. ft. 





Ratio 


Ratio 


1 listain > 










Minimum 


.Minimum 




of cross- 


of cross- 


from 













area of 


Span 


section of 


section of 


bottom 


Approxi- 


1 )iameter 


*Area of 


*Area of 


iteel 




between 


Steel in 


stee! in 


oi slab ti i 


mate total 


of column 


steel over 


steel ovi 1 


between 




centres of 


tension 


compres- 


centre of 


depth 


bead. 


column in 


column in 


columns 




columns 


to 


sion to 


gravity of 


of slab. 




ti 11 [1 m. 


compres- 


per foot of 


per foot of 


in feet. 


concrete 


concrete 


steel in 








sion. 


width of 


width of 




below 


below steel 


tension. 












n < tangu- 




steel. 


in tension. 












band, 


lar band. 




(/>) 


m 


(d) 


(t) 












ft. 






in. 


in. 


ft. 


sq. in. 


sq. in. 


sq. in. 


sq. in. 


12 


o - oi4 


o-oo7 


5 


61 


2-50 


6-6o 


3-3° 


0-20 


0-10 


12 


0-017 


o-oi7 


4i 


5* 


3-25 


9-38 


9-38 


0-21 


o-io 


12 


0-022 


"-033 


3* 


5 


3'75 


11-70 


17-55 


0-23 




14 


0-014 


0-007 


6 


7i 


3-25 


10-31 


5-i6 


0-24 


0-13 


14 


0-017 


o-oi7 


5 


6i 


,V75 


12-02 


12-02 


0-25 


0-12 


14 


0-022 


0-033 


4i 


5i 


4-50 


15-88 


23-80 


0-26 


O-II 


16 


0-014 


0-007 


6| 


81 


4-00 


14-26 


7-1.3 


0-28 


0-14 


16 


o-oi7 


o-oi7 


5* 


7i 


4-50 


16-60 


16-60 


0-30 


0-14 


16 


0-022 


0-033 


41 


6 


5-50 


21-70 


32-55 


0-32 


OT4 


iS 


0-014 


o-oo7 


7\ 


9 


4-75 


18-80 


9-40 


0-33 


0-17 


18 


o-oi7 


0-017 


6\ 


8 


5-5° 


22-92 


22-92 


o-34 


0-16 


18 


0-022 


0-033 


5i 


7 


6-50 


29-70 


44-60 


o-35 


0-15 


20 


0-014 


0-007 


8* 


roj 


5-5° 


24-71 


12-36 


o-37 


0-18 


20 


0-017 


o-oi7 


7i 


8* 


6-25 


29-08 


29-08 


0-38 


0-17 


20 


0019 


0029 


6i 


71 


700 


3135 


4785 


039 


016 


22 


0-014 


0-007 


94 


Hi 


6-25 


31-38 


15-69 


0-42 


0*20 


22 


0016 


0-012 


81 


10 


700 


3490 


2615 


042 


019 


24 


0014 


0006 


101 


12 


700 


3790 


1624 


046 


022 



The values printed in black type are figured for a column head 7 ft. in diameter, and the thickness of the slab is 
increased to withstand the shear.' If the reinforcing rods are so bent that more than 60 lb. in shear can be allowed 
on the concrete, the thickness of the slab may be decreased provided the steel areas are increased sufficiently to give 
the desired strength. 

* Area of steel over column head = circumference of column head in inchesxrfx/> or p' depending upon whether 
the steel is in tension or compression. This steel is assumed as distributed over the entire widths of the bands. Thus 
if a band of steel has 2 sq. in. steel in section, the area, effective, for two bands will be 8 sq. in. (See example.) 

TABLE IV.— DESIGN OF FLAT SLABS. 

Thickness of Slab, Areas of Steel and Sizes of Column Head are Given for Different Spans and 

Percentages of Steel. 
Live Load 300 lb. per sq. ft. 





Ratio 


Ratio 


Distance 










Minimum 


Minimum 




of cross- 


of cross 


from 










area of 


area of 


Span 


section of 


section of 


bottom 


Approxi- 


Diameter 


*Area of 


♦Area of 


steel 


steel 


between 


steel in 


steel in 


of slab to 


mate total 


of column 


steel over 


steel over 


between 


between 


centres of 


tension 


compres- 


centre of 


depth 


head. 


column in 


column in 


columns 


columns 


columns 


to 


sion to 


gravity of 


of slab. 




tension. 


compres- 


per foot of 


per foot ot 


in feet. 


concrete 


concrete 


steel in 








sion. 


width of 


width of 




below 


below steel 


tension. 










diagonal 


rectangu- 




steel. 


in tension. 












band. 


lar band. 




ip) 


(/>') 


(d) 


(0 












ft. 






in. 


in 


ft. 


sq. in. 


sq. in. 


sq. in. 


sq. in. 


12 


0-014 


0-007 


51 


6* 


3-5o 


9-72 


4-86 


0-24 


0-12 


12 


0-017 


0-017 


4i 


si 


4-25 


12-27 


12-27 


0-25 


o-n 


12 


0-022 


0-033 


3i 


5 


5-00 


15*56 


23-30 


0-26 


0-10 


14 


0-OI4 


0-007 


6J 


7i 


4-25 


14-03 


7-02 


0-29 


0-13 


14 


O-0I7 


0-017 


5l 


61 


5-00 


16-84 


16-84 


0-30 


0-I2 


14 


0-022 


0-033 


4i 


5i 


6-oo 


2I-I8 


31'72 


031 


C'll 


16 


0-014 


0-007 


7 


84 


5-00 


18-48 


9-24 


0-33 


0-15 


16 


0-017 


0-017 


6 


74 


6-oo 


23-10 


23-IO 


j5 


0-15 


16 


0-022 


0-033 


5 


61 


7-00 


29-05 


43-50 


0-35 


0-12 


18 


0-014 


0-007 


11 


9l 


6-oo 


24-59 


12-30 


0-39 


0-17 


18 


0-017 


0-017 


6i 


8 


7-00 


29'l8 


29-18 


0-40 


0-16 


18 


0015 


0015 


64 


81 


700 


26-74 


2674 


039 


015 


20 


0-014 


0-007 


8J 


ioj 


7-00 


12-32 


K.-16 


0-4 \ 


0'IQ 


20 


0015 


0011 


84 


10'f 


700 


3365 


2536 


043 


- 18 


22 


0012 


0003 


102 


124 


700 


3400 


8-50 


0-47 


0*22 


24 


0010 


0000 


131 


15i 


700 


3564 


000 


051 


0.25 



The values printed in black type are figured for a column head 7 ft. in diameter, and thi thli I the S 

increased to withstand the shear. ' If the reinforcing rods are so bent that more than 60 lb. in shear 
on the concrete, the thickness of the slab may be decreased provided the steel areas are increased sufficiea 
the desired strength. 

* Area of steel over column head= circumference of column head in inches x,/x/> or p 
the steel is in tension or compression. This steel is assumed as distributed over the entire widths of t 
if a band of steel has 2 sq. in. steel in section, the area, effective, for two bands will be 8 sq. 



SANFORD E. THOMPSON. 



unNUaaM 



EXAMPLE. 

For a warehouse floor with a live load of 150 lb. per sq. ft. and a column 
spacing of 20 ft. each way, what is the necessary thickness of slab, size of column 
head, and amount of steel? 

Solution. — From Table 2 the thickness of slab is given as Si in., the size of 
column head as 5-5 ft., and the area of steel as 247 sq. in. at top of slab and same 
amount at bottom of slab over column, using ratio of area of steel in tension to area of 
concrete below steel as 0*017. Dividing these values by 4, as each end of the bands is 

0.040 
0.035 

0.030 



° 0.025 



0.020 



:0.015 



> 



0.010 



0.005 



11 11111 N 1 lNi h WJiffW 


Hit 1 pFr^ii'i'l 


=j=j= ^^=r— =r 


_ 22 — ~~r~ ~-p 


_j_ z^!xi n — ' 


^1^ 




/&* 






te ?n 


\AJr 








y "^ 




~r "' —1— -1- — U 




_L_ J_ . , 




i 1 1 .11 i ! . 1 ! 



0.000 0.005 O.0IO 0.015 0.020 0.025 0.030 0.035 0.040 
Values of Constant C^ 

Fig. 8. Diagram Giving Values of Constants in Formula 
M 



f* 



Depth of Steel in Compression. 
Depth of Steel in Tension. 



~C s bd 2 



P = 



Area of Steel in Tension. 
Area of Concrete above Steel. 



effective, we have 247 4 = 6-2 sq. in. as the area of steel in each band. For this may 
he used twenty f-in. round bars spaced 5 in. centre to centre for both tension and 
compression steel. 

The amount of steel required at centre of rectangular band is 0^17 sq. in. per ft. 
of width. Placing a |-in. round bar every 10 in. gives more than the necessary area, 
but ease in placing the steel makes up for the extra amount. The amount of steel 
required at centre of diagonal band is 0*35 sq. in. per ft. of width, f-in. round bars 
every 10 in. will thus give necessary amount of steel. 



38 



ffltOCINSTHUCTlONAL] 
[K ENCJINEE.KING — J 



A REINFORCED CONCRETE DOME. 




AN INTERESTING 

REINFORCED CONCRETE 

DOME. 



By DR. A. KLEIN LOGEL, Lecturer in Darmstadt Technical College. 

The effectiveness of reinforced concrete from the point of vieiv of economy in space anc 
from the artistic standpoint is •well shown in the restoration of the dome described in the 
following article. We "would here mention that tve are indebted to the Journal, " Beton 
z>, Eisen," for our illustrations. — ED. 



The health resort of St. Blasien, situated amongst beautiful pine woods in the 
southern pari of the Black Forest, has been celebrated for centuries, and not 
least for its venerable Benedictine abbey, although the latter has long been given 
over in part to industrial purposes. The old monastery buildings are occupied 
by an extensive spinning mill, and only the central building, conspicuous even 
at a distance by its dome (Fig. i), remains devoted to ecclesiastical purposes. 
In 1874, however, an extensive fire broke out in the adjacent spinning mill, 
which also de- 
stroyed the 
wooden frame- 
work of the dome. 
Whilst in 1883 
the outer dome 
thus destroyed 
was replaced by 
one of iron 
covered with 
wood and copper, 
it was only pos- 
sible in 1910 to 
complete the inner 
structure of the 
church — namely, 
by separating the 
interior from the 
iron dome by a 
fireproof rein- 
forced concrete saucer dome. 

The light construction of the outer dome did not permit of suspending 
saucer dome from it. It had also to be taken into account that the outer wa 
and the drum had suffered damage from the fire, so that it was a fund 
condition that the old walls should be spared as much as possible. 

39 




Fig. 1. View of External Iron Dome of the Church. 
A Reinforced Concrete Dome at St. Blasien. Germany. 



A. KLEIN LOG EL. 



(CONCRETE) 




- 



Fig. 2. Left — Original Design; Rigltt — Construction of Saucer Dome finally adopted. 
A Reinforced Concrete Dome at St. Blasien, Germany. 



further conditions connected with the existing structure, so that ultimately a 
shallow construction in reinforced concrete was adopted (Fig. 2, right half), 
which is in the upper part a flat dome of i5'4 metres diameter and 1*5 metres 
rise, and in the lower part a 20-sided tent-vault, of 23'7 metres span and 5'25 
metres height. The upper part is painted with casein colours on a double lime 




Fig. 3. Details of Reinforcement. 
A Reinforced Concrete Dome at St. Bi.asikn, Germany. 



40 



E 



CCNBTROCnONAU 



ENCTNEEJKING 



g] 



A REINFORCED CONCRETE DOME. 



m^^^r^B 






"^fiSS 






jr' 






B S 1 








-^ - *L 


^^^■I^HM ^■^■I^WWP 









Fig. 4. Underside of Unfinished Structure. 
A Reinforced Concrete Dome at St. Blasien, Germany. 



plastering by the artist, Georgi, of Karlsruhe. In this connection 

ing to note that the wood framing of this part was, before concreting, cot 

with crushed granite, free from sand, in order to provide a sufficiently rough 

surface, f r c e 
from cement. 
The tent-vaull 
c oust r uction 
carries a sus- 
pended ceiling, 
or false dome, 
which hangs 
from the main 
structure by 
a bout 2,000 
galvanised 
wires, and 
consists of 
slabs of Duro 
material. These 

slabs are composed of a mixture of plaster with chemical hardening agents and 

vegetable fibre, such as manilla, and are manufactured in Constance up to 

6 square metres in size, and can be reinforced if necessary with steel. 
In order, as 

mentioned above, 

to minimise the 

strain on the old 

walls, a method 

of construction 

was adopted 

which must be 

described as in- 
genious and well 

conceived. The 

lowest tension 

ring of the dome 

bears a stress of 

156 tons. Had 

this ring and the 

ends of the ribs 

been let into the 

brickwork, the 

latter must have 

been considerably 

weakened. I n - 

stead of this, the 

ring- is carried en- 

& Fig. 5. Reinforcement of the Saucer Dome. 

tirely outside the A r EINFOR ced concrete dome at St. b. 




A. KLEIN LOG EL- 



[CONCRET E, 1 



masonry, and is free in space (Fig. 3). Only such connections arc made 
between the ring- and the struts as are necessary, first to suspend the ring and 
secondly to transmit the stresses from the struts to the ring-. This transmission 
is effected by means of special shoes constructed of flat and angle irons. In this 




1 v III I l 

i\\\\\v^UU^Mw\ 

-r- 1 . Lj-1-T- riTlJ.- U H-i 11" i -t-^— t— J-- . — ■ — 





~ a 



way it was only found necessary to provide single supports for the 20 struts. 
each only 00 cm. deep and 1 metre high, so thai the old masonry was cut into 
as little as possible. 

The small saucer dome transmits its weight to the ribs by means of 20 

42 



r y. CONSTRUCTIONAL 
1A ENGINEERING — , 




Steel Scaffolding 



A REINFORCED CONCRETE D 



small vaults (Figs. 4 
and 5). The ribs, again, 
can move over the wall 
by sliding bearings, 
the lower end of each 
rib and the seating 
being each provided 
with a piece of si 
iron, 3 mm. thick, for 
this purpose. In order 
not to endanger the 
masonry by the lateral 
thrust of the structure, 
a straw mat 2 cm. 
thick is placed as a 
cushion between the 
vertical end of each 
strut and the masonry. 
The statical com- 
putation of the entire 
structure was performed 
by Schwedler's method. 
The live load was taken 
as 50 kg. /cm. 2 for the 
Snow and wind were 



saucer dome and as too kg. /cm. 2 for the tent-vault. 

excluded by the position of the structure as an inner dome. The rings and ribs, 




Fig. 9. Saucer Dome Centering partly reinforced. 
A Reinforced Concrete Dome at St Bi.asien. Germany. 



+ 3 



A. KLEIN LOG EL. [CONCR ETE] 

the stresses in which are mainly axial, are treated as columns for reinforcement 
(Fig. 3), whilst the intermediate panels are simply reinforced with straight rods 
(Fig. 6). The reinforcement of the saucer dome is composed of an inner and 
outer steel network, as is best seen in Fig. 9, from which the connections of the 
small dome with the tent-vault may be clearly made out. 

Since the height of the dome above the floor is considerable, special center- 
ing- and scaffolding were required. For this purpose a form of steel scaffold, 
already employed with success in many instances, was used, the details being 
shown in Figs. 7 and 8. Before use the scaffold was subjected to thorough 
loading tests and proved itself then and afterwards in actual use thoroughly 
satisfactory. The scaffolding consisted of steel tubes from 2"5 to 6 metres in 
length and 70 mm. external diameter, 3 mm. thick ; at the joints tubes 50 cm. 
in length were pushed on with a tight fit. In addition, a number of cross- 
connections were provided to give the necessary lateral stiffness. 

The construction of the dome was carried out at the end of 1910 by the 
well-known firm of Dyckerhoff and Widmann, 160 cubic metres of concrete and 
38 tons of steel being used. The architectural design was due to Prof. 
Ostendorf and the State architect, Herr Schmieden The statical computation, 
and especially the idea of the free-hanging tension ring, were due to the 
technical director of the firm, Herr Spangenberg, together with Herr Mund. 
The church is now again in use, and the solution here adopted may lay claim to 
a union of valuable constructional ideas with artistic effect. 



£ 



C&NSTWUC1 ION A Q 
E-NGrNEERlNG 



>NALl 



BILLS OF QUANTITIES. 




RECENT VIEWS ON 
CONCRETE AND REIN. 
FORCED CONCRETE. 



THE CONCRETE INSTITUTE. 



It is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available for reference purposes. 

The method ive are adopting, of dividing the subjects into sections, is, we believe, a 
neiv departure. — ED. 

THE CONCRETE INSTITUTE. 

BILLS OF QUANTITIES FOR REINFORCED 
CONCRETE. 

By JOHN M. THEOBALD, F.S.I., M.C.I. 

The following is an extract oj a paper by Mr. Joint M. Theobald, F.S.I.., M.C.I. , 
read at a meeting of the Institute on November 2&th, Mr. E. P. Wells, the President, 
in the Chair. A lengthy discussion followed, and ivas continued at a subsequent 
meeting on December 12th. Of this discussion a short summary is given. 

GENERALLY. 
After some introductory remarks as to the reasons of the paper and some reference 
to the question of bills of quantities generally, the methods employed in obtaining 
same, the author went on to say that at the present time, when an architect decides 
to construct a building of reinforced concrete he sends a set of plans, sections, and 
elevations to one or possibly more firms of specialists, who then submit a scheme of 
construction under their respective systems, together with an approximate estimate 
of the cost. The firm whose tender is accepted by the architect then prepare their 
working drawings, which, with a bill of quantities (also supplied by them), are sent 
to the contractors, and the accepted tender is either incorporated by the quantity 
surveyor in the quantities sent to the general contractors or is the subject of a separate 
contract, as the case may be. 

REINFORCED CONCRETE. 

Reinforced concrete, from his point of view — namely, that of the quantity survevor 
—has but recently emerged from a healthy infancy; but, now that its employmenl is 
being adopted on all sides, there is a feeling, not confined to the members of his own 
profession, that the specialist contractor should receive the same treatment as the 
builder. 

In advocating the claims of the quantity surveyor in connection with reinforced 
concrete, the author was well aware that he would be told that time does not admit 
of his employment, and that until the details are complete he would be unable to 
commence his work, and the delay thereby entailed might be considerable. Whilst 
admitting the objection, his reply was that, if the building were, for argument's sake, 
a steel-frame building, the steelwork details would have to bo prepared, and he f 
sure that be would be libelling the members of the Concrete Institute by 
that they take longer to supply their details than do the steel manufacturers'. 

Of course, there may be" cases in which rapidity of construct! 
Under those circumstances, the preparation of bills of quantities by a qu 
is impracticable. He may still, however, be advantageously empl 
tion of a schedule of prices and subsequent measurement. 



THE CONCRETE INSTITUTE. [CONCRETE] 

PRESENT SYSTEM EMPLOYED BY CONCRETE SPECIALISTS. 

Under the present system, the quantities issued by the concrete specialists, by 
their own showing, are prepared before the working details are complete, and though, 
granting the necessity (which the author does), he admits that they are in a better 
position to do their work under these conditions than would be the quantity surveyor, 
by reason of their employment of constants and formulae of which he would have no 
knowledge. It must surely frequently happen, however, that in making the various 
details it is found necessary to alter the drawings from which the original quantities 
were prepared, and the latter are, consequently, inaccurate to that extent. 

Under the present regime their correctness is not guaranteed, which, assuming 
for the sake of argument that the drawings from which the building is subsequently 
erected differ from those from which the quantities were prepared, would seem to 
press unduly hard upon the contractor. The contractor is mentioned because the 
author considers the risk in this case is more likely to be his than the building-owners', 
as the alterations would more probably tend to increase the cost of the building than 
to diminish it. It is obviously not a point upon which a quantity surveyor can have 
first-hand knowledge. 

FORMS OF CONTRACT FOR REINFORCED CONCRETE CONSTRUCTION. 
The forms of contract under which reinforced concrete construction is carried out 
are, as far as the author's own experience extends, four in number : — 

i. The " lump-sum " contract, in which the contractor undertakes to erect the 

building for a stipulated amount — no mention being made of the method of 

dealing with any variations that may be made during the progress of the work. 

Anything in the nature of a " lump-sum " contract of this description the 

author thought most unsatisfactory. 

2. The " lump-sum " contract in which the bills of quantities do not form part of 

the contract, but the contractor undertakes to deposit a copy of his priced bill 
of quantities, which, as regards prices only, is to form a basis for arriving at 
the value of any extra or omitted work. 

3. The " lump-sum " contract, in which the bills of quantities form part of the 

contract. 

4. The " lump-sum " contract, in which the bills of quantities form a schedule 

only, and the entire building is remeasured. 
VARIATIONS. 
If, however, he urged the employment of a fully qualified quantity surveyor for 
the preparation of quantities for reinforced concrete, he did so even more emphatically 
when dealing with the question of variations. 

It is apparently not usual for the concrete specialists, who prepare the original 
quantities, to settle the extras and omissions at the completion of the contract. This, 
a. any rate, was the author's experience. The measurement of variations — again 
speaking personally only — is an acquired taste even when dealing with one's own bill 
of quantities, but in reinforced concrete, unless under these circumstances, it is 
anathema. 

Quantity surveyors, from bitter experience of variations, have learnt to " take 
off " with a wealth of detail which would probably surprise many. It would be found 
that, wherea> to the uninitiated the description of the item itself is comprised in half 
a line of utterly unintelligible abbreviations, a further two or three lines are taken up 
by a description of the particular portion of the building in which the item occurs. 

A short time ago the author was appointed by the building-owner to measure the 
variations on a reinforced concrete building, with a firm of surveyors appointed by the 
contractor. The alterations were unusually drastic, and after a preliminary meeting, 
it was agreed that the specialists should be asked to lend their original dimensions for 
the purpose of arriving -it the omissions. Permission was, of course, readily granted, 
bul upon the contractor's surveyor calling for same, he was shown a small sheet of 
paper on which, he was informed, were the dimensions in question. Further inquiry 
elicited the information that the dimensions from which these totals were obtained had 
been destroyed as being of no further use. 

Under these circumstances, of course, there was no alternative but to re-measure 
the omitted work as best possible. Whether the measurements approximated to those 
originally taken is in the highest degree problematical, and whether the building- 
owner or the contractor suffered by the measurement will never be known. 

+6 



[*gSSgSJ£S&%l BILLS OF QUANTITIES. 

This was not a typical case. He did not say for a moment that it is usual to d 
the dimensions when once the totals arc obtained, but he did say thai in rs, by 

tlic very reason of their profession, arc not in a position to take oil the quantities for 
their work. The methods of the modern quantity surveyor .are the outcome oi three, 
if not four, generations' knowledge of the theory and the practice of his profession, 
and it has probably taken him between seven and ten years of constant application to 
acquire it. The education of an engineer- -with which term he, of course, included 
the specialist in reinforced concrete — is even more arduous, and the exercise of both 
professions in the person of one individual seemed to him almost an impossibility. 

ADVANTAGES OF EMPLOYMENT OF QUANTITY SURVEYORS. 

The author then went on to argue whether the employment of a quantity surveyor 
would have obviated any of the disadvantages of the various forms of contract thai 
have been enumerated. 

In the first case, that of the " lump-sum " contract purely .and simply, the 
measurement of the extras by him would, the author ventured to think, result in a 
greater degree of accuracy, and would probably be advantageous from the building- 
owner's point of view. 

In the second case, that of the " lump-sum " contract in which the quantities do 
not form part of the contract, his employment would be amply justified. For anv 
shortage in the quantities he would be responsible to the contractor, and for anv excess 
of measurement to the building-owner. If he was correct in saying that no re- 
sponsibility is taken at the present time, the advantages are obvious, both to the 
building-owner and the contractor ; while, assuming an error against the latter, the 
teinforced concrete specialist would possibly be saved a succession of unpleasant 
interviews. 

In the third example, that of the " lump-sum " contract where the quantities form 
part of the contract, the advantages of the introduction of the quantitv surveyor are 
chiefly confined to the method of " taking off " the original quantities and the conse- 
quent facilities for dealing with the variations. The responsibility is less, admittedlv; 
but the author thought any quantitv surveyor worthy of the name would prefer to take 
the responsibility for the accuracy of his quantities at, of course, a slightly increased 
fee to compensate him for the risk. 

In the last case, where the bills of quantities form a schedule onlv, and the build- 
ing is re-measured, he rather fancied that no reinforced concrete specialist would be 
prepared to give the time to such re-measurement. 

METHOD OF MEASUREMENT EMPLOYED. 

He did not know to what extent Dicthod of measurement may be taken as within 
the scope of his instructions, but he proposed to touch briefly upon the point. 

He had in his office at the present time a bill of quantities, prepared by a firm of 
specialists in reinforced concrete, for a building the cost of which runs well into five 
figures. It consists of three items — concrete, centering, and reinforcement. The latter 
is subdivided into three items of rods or bars in various sizes, but beyond, presumably, 
an inspection of the drawings, this is all the information given to the contractor. 

With the greatest respect, the author ventured to say that no contractor, however 
experienced, can price that bill with any degree of accuracy, and he did not see how 
he could be expected to do so. He was not saying he would not make a profit on the 
job, but he did say that he had no idea what profit. 

The time, however, has now arrived when bills of quantities for reinforced concrete 
should justify their existence and be, in fact, such as will enable the contractor to 
form an accurate idea of the work involved, which, in the author's opinion, he cannot 
do under the present system. 

SUGGESTIONS AS TO METHOD OF MEASUREMENT. 

In making the following suggestions as to method of measurement, he want< 
tc be clearly understood that he was not laying down any hard-and-fast rule- 
idea is to obtain the opinions of members. 

The tendency under the present conditions seems to be to unite as many i 
possible under one description. The author pleaded for a " - 
fuller description of the work involved. 



THE CONCRETE INSTITUTE. [CONCRETE] 

Centering. — In the first place all concrete and centering should be kept separate 

on the various floors. 

The concrete in walls, floors, beams, stanchions, stairs, etc., should also be 
separated. It was not necessary to further subdivide the concrete. The stanchions, 
for instance, if octagonal, circular, or circular on square — the beams if tapering, the 
stairs if flewing — do not entail an additional labour (speaking, of course, of concrete 
only), and there is, therefore, no object in further separation. 

It is on the question of centering that the present system of preparing bills of 
quantities leaves most to be desired. 

The prices of concrete and reinforcement are easily arrived at, and vary but little. 
The centering is by far the most difficult item for a contractor to price, and it is, then- 
fore, absolutely necessary that the description should be as full as possible and every 
variation and labour either measured or described. 

Wall Centering. — Commencing with wall centering — if circular it should be so 
described, and the radius given. Tben, with regard to the vexed question of deduction 
for openings. Unless very large, it has hitherto been the custom to assume the center- 
ing went across the openings, and, consequently, to ignore them. These openings 
should be deducted, and a numbered item taken of centering to openings of various 
widths and heights — averaged where similar in size, but not otherwise. This item has 
been measured per foot run, but, as the ^nief cost is that of maintaining the supports 
of the wall centering in which the openings occur, it is essential that the contractor 
should have the actual sizes — an average of the same would be incorrect because 
misleading. 

Floor Centering. — It need only be mentioned that all raking, or circular cutting 
and waste, should be measured. 

Centering to Beams. — The centering to beams should be measured per foot super 
— circular being, of course, kept separate — including all cutting at angles, etc. If the 
beams are splayed on bottom edge, measure either " Extra labour forming splay blank 
width on edge of beam casing," " Angle fillet blank width and fixing on edge of beam 
casing to form splay," or, take the item " Including all splayed edges"; the latter, 
however, the author considered unsatisfactory. 

If the beams are irregular or unusual in shape, keep the centering separate and 
give a sketch. 

The centering to small beams, say, 18 in. girth and under, measure per foot run. 

Centering to Columns. — The centering to columns and stanchions should be 
measured per foot super, every variation in the shape being kept separate and fully 
described. He preferred to include all cutting in the description, but it can, of course, 
be measured separately, though he saw no object in doing so. 

All extra labour, such as from octagonal to square, number as " Extra over- 
centering for " giving a full description. 

Centering to Stairs. — Centering to stairs should be measured per foot super, as 
" Centering to sloping soffit of stairs." If " flewing," it should be measured 
separately. 

Edges of Concrete Floors. — All edges of concrete floors, well-holes, sides of 
steps, etc., should be measured per foot run, giving the thickness, but if 12 in. thick 
or over, per foot super. 

He need hardly say the description of all centering should include for all necessary 
strutting up from floor below or otherwise supporting. 

The steel reinforcement being only of light bar, he did not think it necessary to 
separate the various weights on each floor. 

Bars. — As, however, the prices of the bars vary according to size, until experience 
teaches which section's could be added together, it was advisable to keep them all 
separate under a heading on the following lin<-s : — 

The following in bar-steel reinforcement and hoisting and fixing at various 
levels (not exceeding blank feet from ground). 

With regard to the question of bends, hooked ends, etc., he was of opinion that, 
where the bar reinforcement is of sufficiently small scantling to be bent cold, they can 
be fairly included in the description, the labour b< ;ing so small that, if numbered, they 

48 



IkSSSSESSStZj BILLS OF QUANTITIES. 

are likely to disproportionately increase the price of the steel. Where, however, they 
have to be forged, they should be numbered. Stirrups and tics should be numb 
giving the diameter and length of the wire. 

It would be advisable, at the commencement of the bill, to describe uch of the 

methods of measurement as might be open to misconstruction by the contractor, as, 
for instance, that all window openings have been deducted from the wall cent 
This will probably only be necessary for a short time; but until contractors have gol 
used to quantity surveyor's methods of net measurement, he considered that any 
information tending to lessen the risk of misunderstanding is wisely given. 

There are, of course, many items which have not been touched upon, but he 
thought he had sufficiently indicated the principle of the method of measurement to 
enable criticism to be made. 

Conclusion. — Should the employment of quantitv surveyors become customary, 
it will undoubtedly lead to a greater degree of uniformity of method of measurement 
of reinforced concrete. At the present time the acquaintance of quantity surveyors with 
the reinforced concrete specialist was not one of long standing, but the author hoped 
this would soon be remedied. 

The President, before the discussion was opened, read a letter from Sir Henry Tanner. 
Letter from Sir Henry Tanner, C.B., F.S.O. (Past-President J. 

" I quite agree with the principles referred to by Mr. Theobald. 

"The practice of inviting design and tenders in open competition is, in my opinion, very 
unsatisfactory ; it leads to cutting down of the most vigorous kind, although the design may 
be within the limit laid down. 

" The quantities prepared by specialists are generally based on the French system, which 
is not very comprehensive in details. It is not unusual' to find a staircase put down as one item, 
whether of stone or wood. This is not what we in England are accustomed to, and the results 
are difficulty in adjusting variations, and, I presume, in the majority of cases the building 
owner suffers. 

" The necessity of dividing the items mentioned is of the greatest importance, because 
while the concrete and the steel can be ascertained definitely as a rule — not always — there is 
nothing to indicate the character of the false work. Therefore, while every care is taken in 
regard to the first two items to keep them within the total quantities provided, there is no 
interest whatever in keeping down the false work. Consequently, when a flat slab might be 
made to meet the case by a small addition of concrete, the builder has to case round raking 
struts projecting on either side. The raking, cutting, and waste involved are patent to anyone. 

" There is another matter having very serious results on the progress of the work, and that 
is multiplication of sections differing by 32nds of an inch in diameter. The mills cannot be 
got to put in rolls for the small quantities involved, whereas there would be no difficulty if 
pains were taken to add a little to some and take off a trifle from others and adjusting distances 
apart. 

" Under the present system the delays that take place at the commencement are appalling. 
The drawings showing the plans and sections, and generally the positions of the beams and 
stanchions, are prepared by the architect, and, together with a specification and conditions of 
contract, are supplied to persons indicating their desire to tender. This labour will be appre- 
ciated by architects, and adds considerably to their expenses. With the tenders are supplied 
some calculations and a few typical details, and the contract having been secured after 
examination of these details, you are at the tender mercy of the specialist, and he suits himself 
on the contingencies of his business as to the supply of the rest. It is the builder who is 
answerable to the building owner, and the specialist can generally shuffle out of any responsi- 
bility to his nominee. The consequence is that the ordering of steel is delayed, and the time 
allowed to the mills is altogether insufficient in normal times. 

" In my opinion the specialist, like the architect, should be ready with the whole of his 
drawings, and the quantities should be properly prepared by a surveyor on the Englis! 
How far the rods should be divided into sizes is a matter rather depending upon price per ton 
than on any other basis, but hoisting certainly has some small effect. I dare say the builder 
would put one figure to the lot, but he has the option of doing otherwise. The rod dian 
should be as few as possible, and the false work, and hence the concrete placed in the forms, 
as simple as possible. I do not believe in varying the proportions of the cement; this 
difficulty and increases the responsibility of the clerk of works, and when one 
in three or four months the concrete has perhaps doubled in strength there is n 
niceties and differentiation. 

E 



THE CONCRETE INSTITUTE. ItolNCJkft SlE 



"If reinforced concrete building is to become popular it must be made as simple as 

possible, whirh means economy and generally is entirely advantageous. 

-■My remarks have wandered somewhat from the scope ot the paper, but still they all 
bear on 'the method to be pursued in tendering. I have had experience of obtaining tenders 
on the basis of general drawings and quantities, omitting the competition for design, and 
these have shown very good results— as good, if not better, than those obtained when com- 
petitive designs and tenders are resorted to. This latter system does not allow the liberty of 
alteration that the former is capable of. 

"I beg to thank Mr. Theobald for bringing forward the subject, as, in my opinion, the 
change is a fundamental one and must come." 

A letter was also read from Mr. Burton, the Engineer to the West Riding of Yorkshire. 

Letter from Mr. W. E. H. Burton, Assoc .M.Inst.C .E., M.C.I. 

" I am much obliged to you for your letter enclosing me a copy of the paper to be read 
by Mr, J. M. Theobald on "Quantities for Reinforced Concrete." 

: ' I have read the same with much interest, and regret that I shall not be able to be present 
at the meeting; however, I have pleaMire in appending a few general remarks on the same. 

"If Mr. Theobald's paper results in the quantity surveyor becoming duly recognised as a 
necessary agent in the carrying out of works in reinforced concrete, it will inaugurate a new 
era that will be hailed with delight by architects and contractors alike. Under the present 
system it is well-nigh impossible to secure satisfactory competitive tenders. The number of 
items in the quantities issued by concrete specialists is too meagre to admit of a contractor 
forming a complete idea of the work required to be done. The labour in bending bars and 
placing the reinforcement varies much in the different systems and is a very uncertain factor, 
and is often misleading to contractors who have not had experience in the particular system; 
hence such disproportionate tendering. Again, variations appear almost a sine qua non, and 
without a carefully drawn-up schedule of quantities an equitable settlement cannot be arrived 
at. 

" Quantity surveying has become a science only acquired by years of training and ex- 
perience, and taking off quantities lor reinforced concrete will call for still further attainments 
on the part of its practitioners. It will mean that they will have to give reinforced concrete 
a closer study, and be at least capable of checking the various schemes they handle, and 
advising the architect upon matters of construction and detail. 

" On the other hand, the quantity surveyor will require the engineer who formulates the 
scheme to supply him with an infinitely greater number of drawings, particularly large scale 
details, than have been considered necessary in carrying out such work in the past. 

" Incidentally it will probably lead to more engineers designing their own reinforcements, 
and not relying so much on the so-called specialists. 

" The result will be to secure contractors a fairer basis upon which to tender, clients full 
value for their money, the architects more facilities in settling up accounts, and thus forward 
the use of reinforced concrete ; and our thanks are due to the author for this able introduction 
of the subject." 

DISCUSSION. 

Mr. A. Whan H. Scott, M.S.A. (Member of Council, Concrete Institute), opened the dis- 
i ussion, and referred to Sir Henry Tanner's remarks with regard to architects receiving com- 
petitive schemes from so-called specialist firms at some length. "An architect is usually 
employed to look after the clients' interests, and he cannot look after his clients' interests if 
he throws the responsibility on to someone wdio is not a trained or professional person. 

' An architect is re-ponsible to his clients if he does not employ a quantity surveyor for 
reinforced concrete work as for other work, and any trouble that might ensue in a building 
contract i> morally thrown back on the architect. 

"Specialists apparently do not attempt to guarantee their quantities; in fact, when any- 
thing goes wrong they do not even attempt to justify them. 

"Regarding the 'lump sum' contract, any contract is fair if it is entered into by two 
sane people and provided there is no pressure on entering into that contract." 

'1 he speaker then dealt with various other points in the paper at some length. 

Mr. T. A. Watson, M.C.I. , thought that at the present time there was too much undue 
haste in the preparation of reinforced concrete schemes, and sufficient time was not given 
to the contractor or the concrete specialist to prepare and price the various schemes. There 
was '""' l,im « ■ '' Mr - Theobald's suggestion was carried out, it meant practically the abolition 
of competition between various reinforced concrete specialists. If Mr. Theobald's scheme were 
carried out lb- architect or the building owner would have to decide on a firm of reinforced 



teaggBSE%£3 BILLS OF QUANTITIES. 

concrete specialists to carry oul the work, or an engineei to design thi irk, and th 
considered, was something very useful gained. 

"There arc some difficulties in the way of carrying oul the scheme, one of which is the 
difficulty that the reinforced concrete specialist or the engineer will have in preparing d iled 
drawings of reinforced concrete work in time to satisfy the client, and in time for the q 
surveyor to take off his necessary particulars, because the- details of reinforced conci 
very considerable and necessitate a lot of arduous work on the part of the enginei 
than is the case with steel -work construction, and where time is of value the onlj method oi 
ing with the reinforced concrete quantities is by the suggestion which Mr. Theobald has laboured 
through, doing a lump sum contract in which the bills of quantities form a schedule and the 
entire building is remeasured." 

Mr. A. Q. Cross, F.SI. (Hon. Secretary, Quantity Surveyors' Association) : There was 
one point he did not think had been sufficiently emphasised by the lecturer, and that was the 
advantage which accrued to the building owner from the employment of the quantity sm 
veyor. After all, it was the building owner who provided employment for the architect, thi 
engineer, and the quantity surveyor, and his interests should be their first consideration. 

" An inestimable advantage accrues to the builder from the employment of the quantity 
surveyor; and the quantity surveyor once being employed, it is his duty to see that quantities for 
every item embraced in the building or engineering structure upon which he may be engaged 
are provided. By no other means can the value of artificers' work be accurately estimated — 
in fact, the surveyor's opinion upon any question of value is usually worthless until the 
quantities are prepared fo<r the particular building. There is nothing in either the workman- 
ship or the materials of a reinforced concrete structure which, from its nature, cannot be 
measured and its value estimated by the surveyor's usual method of picking a complicated 
building to pieces and measuring each item of which it is constructed. 

'" Further, the provision of a bill of quantities usually results in a lower estimate bein;^ 
obtained. This in itself is of advantage to the building owner." 

Mr. S. Bylaader, M.C.I. (Chairman of Council, Junior Institution of Engineers), advo- 
cated a system of simplicity as regards taking out quantities. He suggested forming a 
standard, and it occurred to him that a very simple way was unit prices or unit quantities, and 
that it could be adopted with advantage. For instance, so many square feet of floor at certain 
thicknesses, and so many foot run of beams of certain sizes. The quantifies might also state 
the weight of steel per foot run instead of the total weight of steel. Further, the number of 
bends per ton of steel might be stated, as well as the size of the bars. It was very convenient 
for contractors to price a bill of quantities which contained as few items i.s possible; still, 
the different items should be separated so that they could be properly priced. 

With regard to separating the items for different floors, he did not think this necessary, 
perhaps, for an ordinary sized building, but it was very usful to have the different quantities. 
Mr. T. E. Bare (V.-P. Quantity Surveyors' Assn.) thought everybody would be better oil 
by the employment of quantity surveyors in ascertaining the value of reinforced concrete 
work. One chief difficulty seemed to him to be the question of steel, and with regard to steel, 
and perhaps to steel only, he suggested that provisional quantities be calculated from the 
constants of steel, and there would then be no difficulty with regard to the detailed drawings 
not being prepared in time. He thought a fair estimate of the amount of steel that would be 
required could be arrived at in that way. 

Mr. W. Q. Peiklas (District Surveyor for Kolborn ; Member of Council, Concrete Insti- 
tute) did not think that constants could be used in the way suggested by Mr. Bare. 

He agreed with a good deal of what Mr. Alban Scott had said as to the specialist, 
although he did not go quite as far as he did. He thought that the architect should learn a 
little about reinforced concrete. He should be able to design his floors, his beams, and his 
stanchions in such a way that he would be able to show on his drawings approximately the 
number of bars, their arrangement, and their diameter, the amount of reinforcement to take 
diagonal tension, etc. The quantity surveyor is then able to measure it and put it into his 
bill. That would give the builder something to price, and it would give a basis upon which m 
measure extras and omissions. 

Turning to the question of measurement, the centering of floors should be dealt with in a 
little more detail than Mr. Theobald suggested, but sketches and sections showing the various 
sweeps and bends should be added to the bills of quantities. Further, the steel which ol ' 
in helical or other curved reinforcements should be kept separately from the straight. 

Mr. R M. Kearns quite agreed with Mr. Theobald in advocating that quantity sun 
should prepare the bills of quantities for reinforced work, but it seemed to illy in 

stood that the patentees of the different systems insisted on the use of quantities prepar 
their own experts. This, for various reasons, was not a satisfactory state of 

E z ;i 



THE CONCRETE INSTITUTE. [CONCRETE] 

highly probable that the client would obtain closer and more favourable estimate, <™ cor, 
tractors if they were supplied with bills of quantities winch would J™ them a reasonabh 
accurate idea of the work required to be done under the terms of the contract. 

The matter was one of deep interest to quantity surveyors, for it was evident that the 
employment of reinforced concrete was rapidly increasing. 

With eference to the items proposed to be inserted in bills of quantities, he did not agree 
with Mr Theobald on every point. Labour items should be discarded as much as possible 
They were iikely to be over-priced so far as the centering was concerned, the latter to a large 
extent being only chargeable as « use and waste." It was not customary to measure the labour 
on centering in connection with the stonework in Gothic window and door openings. 

All the concrete walls and floors should be supered, keeping each floor separate. 1 he 
concrete in beams and piers might be cubed. . , ... , , no9 

The centering to walls and floors should be measured over all surfaces and billed at per 
square or foot super. The casing to beams and piers, cornices, jambs, etc., might with 
advantage be measured at per foot run, stating the girth and giving a figured section m the 
margin of the bill showing any angle fillets or splay cutting. 

With reference to the reinforcement itself, the whole of the steel bars, loops, stirrups, 
or ties should be weighted and billed at per cwt. There should be no numbered items. When 
wire is used for binding it need not be measured, but should be mentioned. In short, the price 
quoted per cwt. for the reinforcement should cover the whole of the smiths' materials and 

labour. 

Mr. W. B. Divis (M. Quantity Surveyors' Association), after dealing with Mr. Alban 
Scott's remarks and some general references to quantity surveyors, said, with regard to the 
centering, there was one point which offered difficulty, and that was the re-use of centering. 
For example, take a warehouse with, perhaps, five or six floors ; it made a very great difference 
to the cost of the centering as to the number of times it could be re-used on the same building 
without a large allowance for waste. 

Mr. George Corderoy, Assoc. Inst. C.E., F.S.I., MCI.: "The difficulty which is ex- 
perienced in taking out quantities for reinforced concrete work really resolves itself into 
this, that the system of reinforcement to be pursued has so seldom been settled before the 
tenders have been invited. The practice which has largely prevailed hitherto has been to invite 
the estimates for various systems of reinforced concrete for the same building or for the same 
structure. 

•■ In dealing rather extensively with reinforced concrete work in different forms — monu- 
mental buildings, warehouses, jetties and wharves, etc. — at any rate in the present state of 
knowledge and in the present welter of systems — it does not seem possible to lay down any 
absolute method of measurement, as the methods of measurement must necessarily vary 
according to the nature of the building to be erected." 

Mr. W. R. Hood, F.S I. (M. Quantity Surveyors' Assn.) ; said: "Speaking from personal 
experience, detailed quantities should be taken out for special work, for which, up to recent 
times perhaps, large sums — provisional sums — have been put into the bills of quantities. In 
reinforced concrete work the same would have to be done as has hitherto been the case with 
iron constructional work. 

"" The subject of the paper that Mr. Theobald has read will certainly lead to considerable 
discussion in the future in another place— in fact, in two places; for surely the Surveyors' 
Institution should feel it incumbent upon them to call a meeting of their own members and 
the Quantity Surveyors' Association and, with the assistance of the reinforced concrete 
specialists, formulate a system of measurements which will be generally adopted. 

"There is, undoubtedly, an element of speculation in the present system. If a specialist 
is invited to give an estimate for a particular system of reinforced concrete work, he naturally 
takes out the quantities in such a way as to cover him for any contingencies that take place, 
and therefore the estimate that he produces is not an accurate estimate of the work that has 
to be carried out. There are variations in the general drawings and the detailed drawings, 
after the quantities have been prepared by the specialist, and those variations, if not adjusted, 
undoubtedly benefit the reinforced concrete specialist, not the building owner." 

The President showed a method which he had adopted for several years in taking out 
quantities, and, as a rule, the origin;,] quantities can be taken if they were asked lor at any 
time, and every measurement checked from start to finish. 

Taking, as an example, one tiling only — a column— and assuming, for the sake of argu- 
ment, that the base being dealt with inclined at an angle of 45 degrees. In taking out 
(pi. unities, this is the method he adopted. Paper that is specially ruled divided up in five 
columns [illustrating on blackboard!. For the sake of argument, let the firsl column repre- 

52 



(I 



ODN-STTJUCTlONAi; 
EMOfNEXRlNti — | 



BILLS OF QUANTITIES. 



sent concrete, the next represent shuttering, the third represent steel, the fourtl 

the abstract or the analysis — this is the rate column — and the last istlicUii.il in p 

and pence ; thus giving every detail of the quantities from start to finish. It is not a here 

of taking out quantities all over the place, then starting afterward- and abstracting tl 

and that is where so many mistakes are made. 

Taking the first item — concrete. Give its area by its thickness and reduce it down to i ubii 
feet. 

Dealing with the next column — the measurement for shuttering [illustrating]. Now, if the 
angle is 33 degrees, shuttering for that base is not required, as the concrete will stand up, 
but if it is to be 45 degrees the concrete will not stand up; therefore it becomes necessarj to 
put a subheading under " shuttering," for the simple reason that the extra cost of making the 
shuttering on the splay is caused by the cutting of the angles and the holding of the whole 
together. 

The steel column shows the whole of the steel — sizes of bars, their lengths, their weights, 
and also the shear members. This gives the weight of the steel in the base. 

This finishes the base of the column, with everything taken out — its concrete, its steel, it> 
shuttering, both plain and splayed. Then carry the totals into the abstract column, also if 
there are any labours; but, as a rule, in column bases they are absent. In taking out proper 
bills of quantities, this gives everything for the abstract without having to refer to back sheets. 

Regarding the column shaft, the same method applies. First take the concrete, then the 
plain shuttering, the splayed shuttering under a separate heading; then take the steel in plain 
rods and any hooping or linking under separate headings, all of which is abstracted in the 
fourth column, as well as any extra labour, etc. 

This same method can be applied to every description of work. If by any possible 
chance there was any circular work, it was taken as an extra foot super on the ordinary work. 
When it came to windows, the deductions should be made for the window area, and it should 
be stated in the quantities that everything was net, notwithstanding any trade custom to the 
contrary. He contended that this system, if followed out in its entirety from start to finish, 
made reinforced concrete quantities the easiest to take out of any work. 

He recommended that all quantity surveyors should depart from their usual method of 
taking out quantities for this work. 

ADJOURNED DISCUSSION. 

The President, in continuation of his remarks of the previous week and in accordance with 
requests received by him as to the method he employed in taking out quantities for rein- 
forced concrete work, had prepared a cartoon illustrative of his system. This cartoon simply 
represents the sheets that go out to a contractor when he applies to him to get out designs and 
quantities for the work. With the aid of the blackboard, the speaker then further amplified 
his remarks of the previous week. The method clearly indicates the necessity of separating 
out the different items, such as steel, shuttering, concrete, column work, etc. 

He then called upon other members to continue the discussion. 

Mr. R. W. Vawdrey, B.A. (Assoc. M. Inst. C. E. ; Member of Council C.I.), said he was 
connected with a specialist firm, and entirely agreed with all that was contained in Mr. 
Theobald's paper. The whole position of the question of designing reinforced concrete work- 
in competition as it exists at present is most unsatisfactory, due to a very great extent, he 
thought, to the absence of the regularised method of dealing with the matter that obtains in 
nearly all other classes of construction. 

The great difficulty and the great amount of dissatisfaction which occurs in connection 
with the design of reinforced concrete work is owing to the fact that contractors are asked 
to tender not upon one set of designs or one set of quantities, but on many such designs, all 
differing from each other. It is that which induces the chief objection there is to the present 
system. 

As regards the question of time, everybody who has had any experience with the question 
would agree with Mr. Theobald that the specialists concerned — that is, those firms who make 
it their business to design in reinforced concrete — will welcome with open arms the introduc- 
tion of the quantity surveyor. As is pointed out in the paper, the employment of a quantity 
surveyor merely relieves the concrete specialists of a great deal of elaborate work tor which 
they are not so well fitted as a quantity surveyor, and, of course, it relieves them also of tl 
responsibility. 

As regards a separation order, this is a very good point, and has been elaborated 1 
President in his remarks. The more the quantities and the different portions of the structure — 
the fittings, columns, beams, etc. — are separated, undoubtedly the clearer and the chi tper it 
is. 

5.1 



THE CONCRETE INSTITUTE. [CDNCRETEj 




or hepu rpo a -a eci is firm of designers, things would be very much simplified At 

presen in Z great majority of cases, architects or quantity surveyors acting for thai client. 

almos" invariably ask trie specialist firms to submit tenders. That is, of course, absolute ly 

n or ect The specialist firm does not. except in a very few instances, submit tenders. 1 he 

realist firm is a firm whose existence is for the purpose of designing reinforced concrete work. 

Mr Frederick Hingston (M. Quantity Surveyors' Assn.) : There are one or two more points 
to be mentioned with regard to the taking out of quantities for reinforced concrete work. 
First, with regard to the concrete work itself, the speaker said he did not agree that small 
rods should be taken, unless they are very numerous. 

As regards the centering, this should be given at per foot run, giving the sizes of the 
beams where possible. Of course, where the sizes differ very considerably they might be 
averaged Shuttering should include the triangular fillets and any labours upon them. As 
regards the larger steel work, the labours on them should be taken and the whole of the steel 
work should be kept separated under its different sizes. 

There was one other point not mentioned by the lecturer, and that was the finishing of the 
concrete. He assumed the lecturer would take that separately and treat it very much as the 
quantity surveyors do— namely, the plaster or similar finishing on the inside and whatever 

facing is on the outside. 

Mr. G. C. Workman, M.S.E. (Member of Council, Concrete Inst.), speaking from the point 

of view of an engineering designer working under a patented system, ventured to make the 
following remarks : . 

First of all, he was very pleased to see that Mr. Theobald states quite clearly that he is 
making no reflection upon the quantities supplied by the engineers under the present system, 
and that his criticism is solely directed against the actual method of dealing with reinforced 
concrete work, and not against its exponents. As a matter of fact, the reinforced concrete 
engineers are directed by circumstances over which they have very little control, and they 
would in many cases welcome the help of a quantity surveyor. He personally had endeavoured 
for many years to bring about a collaboration between the reinforced concrete specialist, the 
architect and the surveyor. Unfortunately, the engineering designers are depending upon the 
requirements of their clients, and competition prevents each individual firm of engineers from 
attempting to dictate the proper course which the client ought to follow for the mutual benefit 
of all concerned. 

Regarding the lecturer's remarks as to the correctness of the quantities not being guaran- 
teed, the speaker stated that most of the firms of engineering designers working on similar 
lines to his — the Coignet system — must guarantee the accuracy of the quantities, or at least of 
the unit quantities of concrete, steel and centering for each element of the construction. It is 
evident that, under these circumstances, taking into account the fact that the work must be done 
in many cases with extraordinary rapidity, there is a considerable amount of risk. The point 
is, assuming that surveyors would be willing to take out the quantities very rapidly of a 
large number of competitive schemes throughout the year, would they be prepared to take the 
financial responsibility for the accuracy of their quantities, and also to do this on the under- 
standing that they would not receive any remuneration whatever for all those schemes which 
the firm of engineers in collaboration with whom they were working were not successful in 
securing? 

Uefore anything practical can be done in the direction suggested by Mr. Theobald, it will 
first be necessary that quantity surveyors should make an exhaustive study of the various 
systems which are at present continually in competition for works in reinforced concrete, and 
also that they should solve the question ais to whether or not they are prepared to work in 
collaboration with the designers, on the same speculative terms as the latter are compelled 
to adopt on account of the fact that they see no other alternative. 

Mr. Theobald states that the methods of the modern quantity surveyors arc the outcome of 
the knowledge of three or four generations who have had constant practice in this profession. 
Unfortunately, the quantities for reinforced concrete are quite different from anything 
to which surveyors are accustomed, so that the experience of all their ancestors will be of 
very little avail to them. In fact, unless a quantity surveyor has a perfect knowledge of the 
particular system of reinforced concrete for which he has time to take out quantities, he is 
far less capable of doing this work properly and rapidly than the specialist engineer. 

In conclusion, the entire question concerning the employment of quantitj surveyors in 

54 



(jjgfgjglg BILLS 0F QUANTITIES. 

conjunction with reinforced concrete chiefly depends on whether or nol the quanl I 
. i rt* willing to take the Name responsibilities and run the same risks as the speciali 

Mr. Moritz Kahn, M.C I., thought Mr. Theobald lias the honour of haying pr< ented om 
ol the most interesting papers that lias been read before the Institute. 

He, too, hoped thai sooner or later the quantity surveyor will take an active part in the 
measurements of reinforced concrete work. 

The preparation of quantities for reinforced concrete work is probably moi te than 

the preparation of other quantities. Each designer has his own method of detailing the work. 
These methods differ to a considerable extent, and standards which might Ik- drawn up for one 
designer will not apply to the other. The measuring of the concrete and steel in the respective 
items is a simple matter, and under ordinary circumstances the measuring of ((altering is a 
simple matter; but the ordinary circumstance is not the rule, with the result that, speaking 
offhandedly, it is a difficult matter to generalise a method of measuring quantities of (entering. 
It seems that satisfactory results can be obtained by giving the contractor general measurements 
of the centering and submitting with the measurements such drawings as will enable him to 
understand the nature of the work he will be called upon to perform. After carefully studying 
such drawings, his experience ought to teach him how to price the centering. 

The present method adopted by the specialist is one which has been forced upon him by 
circumstances over which he has no control. 

Mr. Percival M. Fraser: As a quantity surveyor he took exception to a few 7 remarks that 
Mr. Theobald had made. He did not think there is one client in a thousand who ever sees 
the bills of quantities, and a client would not pursue them with any great gratification. 

Regarding the lecturer's remarks as to the procedure adopted by the architect deciding 
to construct a reinforced concrete building, he thought this was quite wrong. He saddles an 
architect with this somewhat undesirable method of carrying out a concrete building. He 
might have included engineers. Architects do not adopt this method. The concrete specialists 
themselves are beginning to freely state that they think the spirit of competition is very 
iniquitous. Every day seems to show a falling off in the desire of architects to have their 
concrete schemes prepared in a spirit of vulgar and elbowing competition. In regard to the 
specialist's approximate estimate, it can be done by special request; but surely it is not the 
common practice that Mr. Theobald states it is. With regard to the quantities supplied by 
specialists, this is absolutely universal. The specialist should, however, absolutely refrain 
from giving quantities unless he is prepared to give them by employing quantity surveyors 
trained up in the office. 

Mr. Theobald, in quoting the forms of contract, might also have included the R.I. 15. A. 
form, which is admitted by lawyers to be one of the finest forms of contract extant, applying 
to any business or trade ; and he might have stated — which is of vital interest — that this 
R.I.B.A. form is issued under two headings, one Where quantities form part of the contract 
and one where they do not form part of the contract. 

There is also another form of contract which has been omitted — a very important 
one largely used for alterations — prime cost plus profit. It is a highly complicated form, but 
in many cases it is exceedingly valuable, and it should have been mentioned in an authoritative 
paper of this sort. 

The whole trend of this paper is, and quite rightly, a plea for the employment of quantity 
surveyors. 

MR, THEOBALDS REPLY. 

Mr. John M. Theobald, F.S.I.', M.C.I., said his paper had been rather under a mis- 
apprehension. He certainly meant it as a justification for the employment of the quantity 
surveyor and only very little of it was on the methods of measurement. Most of the speakers 
have dealt at length with the methods of measurement, and consequently the greater part of the 
paper, except by one or two speakers, has not been touched upon. 

The general consensus of opinion seemed to be that No. 4 form of contract was the most 
practical outcome of the methods of measuring reinforced concrete work. That is the ancient 
schedule of subsequent measurement. 

Then, dealing with Mr. Hare's criticism in regard to the question of steel work, ot course, 
in initial quantities, he admitted it was necessary to ask the weight per foot from the 
specialist. If the contracts are not prepared they cannot be [nit in by any other method. 

With regard to Mr. Reams' criticism and his suggestion of measuring beams per foot 
round, he could not quite agree. He thought Mr. Kearns a little inconsistent bi 1 
for a shorter bill of quantities, and then running all the beams in various ! ions. 
would make a very long bill. He did not think it mattered very much if tl 
same and only the widths are averaged, but he did think the superficial m< 

55 



THE CONCRETE INSTITUTE. [CONCRETE,] 

way of dealing with it. In regard to Mr. Kearns' suggestion that all the -oncrce walls and 
floors should be included in the superficial, he did not see that it could be done. 

Mr. Davis's point as to the rules of centering for concrete is one which lie was afraid 
quantity surveyors could not deal with. They must measure the entire amount of centering 
and leave it to the contractor to make such reduction in the price he thinks necessary. 

Mr. Workman wanted to know whether quantity surveyors would be prepared to deal 
with quantities under the circumstances that he mentioned. The answer is in the negative. 

In regard to Mr. Fraser's remarks about the question of clients seeing bills of quantities, 
it was the variation account he (the lecturer) referred to. 

Regarding the two forms of contract omitted, they should, of course, have been 
mentioned. 

Then as to the question of net measurement, that is a direct contractor's question. It is 
the very last item : but what is intended by net measurement is this : in the rough and ready, 
quantities have to be prepared in a rush at the present day by competition. For instance, 
the stanchions would go right through the floor, and then the floor would not be deducted 
for the passing of the stanchions. That is the sort of thing meant by net measurement, and 
it is understood by contractors. 



d 



CONSTKUCTIONA l.l 
ENCINt. EKING — J 



A REINFORCED CONCRETE RISING MAIN. 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reliable information "will be presented of neiv "works in course of 
construction or completed, and the examples selected ivill be from all parts of the "world. 
It is not the intention to describe these "works in detail, but rather to indicate their existence 
and illustrate their primary features, at the most explaining the idea "which served as a basis 
for the design. — ED. 



A REINFORCED CONCRETE RISING MAIN. 

The accompanying illustrations show a rising main in reinforced concrete al Luton, 
Bedfordshire. This main is about one mile long, and has an internal diameter of 
about 27 in. The skin thickness of the concrete is 3 in., and the steel reinforcement is 
2.3 per cent, of the volume of concrete. The pipe has no lining of any kind, and 

according to a test made by 
the borough engineer <>f 
Luton, the pipe after having 
stood full for 12 hours lost 
such a small quantity of 
water that he considered the 
same to be perfectly water- 
tight, especially bearing in 
mind that the valve which 
closed the bottom end of the 
main could not be seen and 
might not have been abso- 
lutely watertight. The pipe 
also underwent a test of 60 lbs. 
pressure per sq. in. continu- 
ously for six months on the 
contractors' premises before 
delivery. The work was 
carried out under the super- 
vision of the borough engi- 
neer, Mr. J. W. Tomlinson, 
M.Inst.C.E. ; and the con- 
tractors were the British Im- 
proved Construction Co., Ltd. 

A REINFORCED CONCRETE 
INCINERATOR. 

The Incinerator measures 
2 ft. in. by 2 ft. o in. inside, 
and the height from the fire- 
bars to the bottom of the feed 
door is 2 ft. 

The whole, with the ex- 
ception of the doors, firebars, 
and lop of flue, is made of 
reinforced concrete. T h e 
walls are 4 in. thick, and the 
Hue :\m\ arch are 3 in. thick. 

The concrete is 1 Port- 
land cement, 2 sand gr 
4 stone ballast up 
Each side is mouldec 
rately, the back, side, and 
bottom of flue beii 
A Reinforced Concrete Rising Main at Luton. in one. Th ■ nietit 




NEW WORKS IN CONCRETE. 



[ CONCRETE] 



consists of two layers of 5 in. wire netting, ii in. from the face inside and 5 in. from 
the face outside. For the reinforcements across opening | in. round bars arc used. 
I'i the back piece \ in. round bars are run up into the front of the flue, the sides of 




Showing Main under Test. 
A Reinforced Concrete Rising Main at Luton. 



the flue having diagonal J in. round bars securely fastened to the bars in the back 
piece of the chamber and to other bars in the back side of the flue. 

In the arch, which is moulded on the centering, wires are run across along the 
course of the arch from the 
rods left projecting in the side 
pieces, and \ in. rods from 
the front to the back pieces. 

The various sides are 
moulded at site, with steel 
feet, which are embedded in 
lime concrete. When the 
sides are in position the pro- 
jecting portions of the wire 
netting are tightly interlaced 
and the corners filled in with 
concrete. 

The arch is then moulded 
on centering. The firebars 
are made up in three sections, 
which are removable for re- 
pairs, and which rest on steel 
lugs moulded into the sides. 
The upper of the two doors 
shown in the flue is for a 
grass filter for the smoke 
Dry grass is put on wire 
netting which extends across 
the flue, and this catches niosi 
of the oily substance in the 
smoke which gives it its un- 
pleasant smell. These particu- 
lars and illustrations were 
placed .'it our disposal bv a 
correspondent in India, Cap- 
tain P. N. Kealv, R.E. 




)RCED Concrete Incinerator in India in Courm 01 
Construct!' >n. 



58 



& CONSTRUCTIONAL. 
, ENGINEERING — '. 



REINFORCED CONCRETE RETAINING WALi 



A REINFORCED CONCRETE RETAINING WALL. 

Our illustration shows a new reinforced concrete retaining wall recently i 
at Basford, in Staffordshire, in place of an existing one which had show, 

failure in differenl plai 

As 1 1 msiderable improve- 
ments are to be effected in this 
locality in the future, the new 
reinforced concrete wall was 
designed to carrj all the 
pressure that was ever likely 
to come upon it, and that pari 
of the wall shown under con- 
struction in the illustration 
attains a maximum height of 
20 ft. above future ground 

level. 

It was essential thai the 

high-level road should be 
interfered with as little as 
possible. Buttresses were, 
therefore, out of the question, 
and a cantilever wall was 
adopted with a base project- 
ing under the low-level road, 
about 2 ft. beneath future 
road level. 

The work was carried 
out under the instructions and 
superintendence of t h e 
borough engineer of Stoke- 
on-Trent, Mr. A. Burton, 
Assoc.M.Inst.C.E., to the 
designs of the Indenti d Bar 
and Concrete Engineering 
Co., Ltd. The contractors were Messrs. F. Barke & Son, of Stoke-on-Trent. 

A REINFORCED CONCRETE TANK AT A CURRENT METER RATING 
STATION AT CALGARY. ALBERTA, CANADA. 

We present herewith some particulars of a reinforced concrete tank, forming part of 
a current meter rati>ig station at Calgary, Alberta. 

In designing the work for this station the aim was to gain the most perfect apparatus 
possible for rating the current meters and to create a permanent structure, so that it 
was early decided to use concrete in the construction of the necessary tank. 

As no stretch of still water having a suitable length and depth was available, it 
was necessary to creak- a tank, and in studying its design two points had to he 
principally considered. First, as the water supply had to he taken from the city main-, 
the tank had to be made proof against any leakage. Secondly, the cross-sectional 
water area was required as small as possible and yet of sufficient dimensions to guard 
against any following on movement of the water, in running the meters through the 
tank. To'overcome the first difficulty a heavily reinforced structure was designed, 
such that being emptied ami exposed to the weather in winter no temperature crack- 
could develop," and the inside faces of the tank were water-proofed by Sylvester 
process. In deciding on the proper cross-section of the tank to overcome the secoi 
difficulty no data were obtainable, hut with the tank as constructed no followin 
movement or undue disturbance of the water has been observed even with the 1 
meters tested at velocities as high as 10 ft. per second. The length 1 
(250 ft.) was adopted in order to bring the cost of the structure within the 1 
amount of money available, but provision lias been made in local' 
future extension to a length of 500 ft , which is desirable in order ti 
degree of accuracv. 




Completed Structure. 
A Reinforced Concrete Incinerator in India. 



NEW WORKS IN CONCRETE. 



(CONCRETE, 



The concrete tank is 250 ft. long with an inside width and depth of 6 ft. bv 
5 ft. 6 in., and the depth of water to be maintained is 5 ft. The floor and walls are 
8 in. thick and are reinforced heavily, longitudinally and transversely, with i-in. round 
mild steel rods, in order to absolutely preclude any temperature cracks in the concrete. 




The concrete was specified a mixture of one part Portland cement to seven parts clean 
river gravel, to have at least fifteen turns in a good machine, and to be placed we! and 
thoroughly tamped. All the interior faces wen' thoroughly spaded in order to create 
a smooth close-grained surface, to which to apply the Sylvester's wash. All steel rods 

60 



fj r constructional' 

\C I ENC.l 



REINFORCED CONCRETE TANK. 



■ ENGINEERING — j 

at joints were overlapped 16 in., and it was specified thai they were to be wired so as 





t — i 

nr.l. .1.. ' 

1 



s= 




IN 


1 




ll 




~? 




r : 


•J 
[ 


'*> 


X 


< 


*Ss J 


J- 




.. .,s 


T I 



have contact throughout the whole of this length. The tank flooi 

6i 



NEW WORKS IN CONCRETE. 



[CONCRETE 



S-in. foundation of Large stones overlaid with smaller stones and gravel, in order to 
provide thorough drainage for any water which might leak through the lank, so thai 
when the tank is emptied in winter and exposed to the weather no heaving might 
result from any water being lodged under the tank bottom. The soij beneath is of 

sandy character, which is permeable to water. The water supply is from a 2-in. iron 
pipe laid from the city mains, and a 6-in. tile drain 224 ft. long, fitted with an iron 
gate valve at the tank, allows the tank to be emptied a! any time into the river. After 



1-r- 



~# 




Reinforced Concrete Tank for Ccrrent Metfr Rating Station. 



the tank was completed all the inside faces were treated with two coats of Sylvester's 
wash. Up to the present the tank has been twice exposed empty to severe cold with 
the thermometer at — 30 , mid no cracking of the concrete whatsoever has resulted, 
except a few hair-line cracks near the top of the walls. As regards the water-proofing, 
two observation shafts were left along the tank sides running down to the foundation, 
and no leakage whatever was observed during the summer when the tank was full, 
except a slight dampness at the bottom of the side walls. It should be noted that 




General View. 
Reinforced Concrete Tank for Ccrrent Meter Rating Station. 

another reason why it was desired to make the tank leak-proof is that it is intended to 
obtain evaporation records at the lank in future seasons. 

This work was carried out for the Irrigation Office, Department of Interior, 
Alberta, Canada, under the supervision of the Chief Engineer, Mr. F. H. Peters, 
A.M.Can.Soc.C.E., to whom we are indebted for our illustrations and particulars. 

A HOUSE OF CONCRETE BRICKS. 

Our two illustrations show the back and front view of a house erected in Hove, near 
Brighton, in concrete bricks. Red concrete facing bricks have been used up to the 
first floor and for the chimneys. The proportion of mixture was seven parts sea sand 
tj one part cement. Natural concrete bricks were used fur the rough cast part. 
62 



f J. CONSTKUCTIONAU 
[t\ ENGINEERING j| 



HOUSE OF CONCRETE BRICKS. 



These bricks consisted of lour parts sea sand, four part-, coke breeze, and one 
cement. The bricks used were those made on the machines of Messrs. R. II. 
Baumgarten, of Lewisham, S.E. 




Back View, 




Front View. 
Concrete Brick House, Hove, near Brighton 



6; 



CORRESPONDENCE. 



( CONCRETE) 



CORRESPONDENCE. 

Under this heading ive invite correspondence. 

Beloiv vie print a letter relating to the London County Council's administration of the 
London Building Amendment Act, 1905. We, like several other technical journals, have 
received this communication, "which sets out the approximate number of existing buildings 
requiring attention, the causes to ivhich the present state of affairs may be attributed, and 
some suggestions as to how the existing dangers may be remedied. 

We referred to the sibiect editorially in our previous issue, and in the current number 
ive have also accorded an editorial notice to this matter. 

Our columns are open to those vj'w desire to criticise figures given, to those iv'w ivish 
to reply to the indictment, or desire to comment upon the suggestions made. — ED. 



FIRE PROTECTION AND THE LONDON COUNTY COUNCIL. 
How the Council's Existing Powers could he enforced ■without undue expense cr delay. 

Sir, — A full month has elapsed >incc the fata] Kensington fire. 

One would have thought the London County Council would have been mosl 
anxious to prevent the repetition of such loss of life occurring again in the many 
existing buildings of a similar character. 

But both in the Council Chamber and in the Press the Chairman of the Building 
Act Committee of the Council appears only to be anxious to find excuses for its lack 
of activity in administering the Building Acts (Amendment) Act of 1905, by giving 
entirely non-relevant information as to the supervision of buildings about to be erected 
— as distinct from existing buildings — the number of inspections made under the 
Factorv Acts, etc., i.e., useful, but entirely extraneous activities of his Department. 
His aim also seems to be to belittle the number of existing buildings requiring the 
attention of the Council, while on the other hand, exaggerating the difficulty of the 
character of the work that has to be done. 

Regarding the figures that I have put forward from time to time in the Press and 
elsewhere, as to the number of existing buildings requiring attention and the very 
small proportion of these buildings that have been put in order during the past seven 
years, the London County Council has not been able to contradict those figures, or put 
up anv other pertinent ones in their place, and I would thus now summarise my data 
once more as indicating the Council's extraordinary lack of energy in providing for 
the safety of the public. 

My figure^, to summarise, are as follows : — 

(i) There have been 48,566 cases notified by the District Surveyors to the Council 
under Sections 10 to 12 of the 1905 enactment as requiring the Council's 
attention. Of these only 351 cases have been put in order so as to comply with 
Section 11, and only 4,430 cases have either been exempted, or ordered to be 
improved under Sections 10 and 12 of the Act. The balance that remains and 
awaits attention is thus close on 44,000 cases. 

(ii) There are further well over 50,000 buildings awaiting attention under Section 
9 of the Act, and of these only 527 have been put in order in the past seven 
vears (i.e., up to June 12th last), together with, say, an additional 100 up to 
date. In other words, over 49,000 buildings are still awaiting attention under 
this Clause. 

Bluntly, this means that there are to-day between 93,000 and 94,000 existing 
buildings which have been awaiting for seven years the Council's pleasure, and 
the majority of these buildings might have been put in order by this time 
without anv very great effort on the London County Council's part. 

Now without touching on questions of hidden policy or municipal politics, the 
known causes for this state of affairs comprise the following : 

(1) A lark of co-operation and mutual confidence between the Council and the 
building owners. 

(2) A lack of co-operation between the Council and the 50 statutory Districl 
Surveyors who are not actually their employees and a certain amount of 
interference on the part of the Council in the District Surveyor's work. 

(-1^) An absence of all energy or earnest in the matter on the part of the Council 

64 



feasssssaa correspondence. 

per se as distinct from their technical officers i.e., their Superintending 
Architect, Assistant Architect, and Committee Clerk, all men i I ional 

ability and high purpose. 

(4) A lack of industry and savoir fane on the one hand, and much " wood 
on the other, in the Council's Building Act Committee. 

(5) An extraordinary undermanning of the Building Act Department, having 
regard to the work thai it should attend to, and particularly an insufficient 
number of suitably paid managing assistants i.e., Deputy Assistanl Architects. 

(6) A general public impression fostered either purposely or unwittingly by the 
Council — that the Act is a " dead letter." 

It is, however, no use complaining of the Count_\- Council's failings without indicat- 
ing some practical and economic remedy useful alike to building owner rind public 
authority. This remedy, to my mind, is a very simple one, and comprises the 
following : — 

(a) A public announcement in the Press (to be repeated monthly) that it intends 
to have the whole of the work under the Building Acts (Amendment) Ai 
1905 remedied by January 1st, 1918, the public announcement to be followed 
by two circular notices in the 44,000 notified cases under Sections 10 to 12. 

(b) An immediate instruction to the District Surveyors to notify to the Council, 
say within six months (as set out in Section 17) all cases they consider to come 
under Section 9 — a matter that has been practically neglected during the past 
seven years— and immediately upon receipt of these notifications an issue of 
two circular notices to owners concerned that the Council are prepared to 
receive suggestions accompanied by plans with proposals as to convenient 
dates for carrying out the necessary structural improvements, and are prepared 
to assist in every possible way applicants who volunteer plans and offer practical 
remedies. The circular notices should indicate certain primary principles 
desired by the Council, such as alternative routes of exit from workshops ard 
dormitories. 

(c) A cancellation of the existing embargo that the fifty District Surveyors an- not 
to press the execution of work under Sections 10 to 12 in their respective 
districts, and in place of that embargo an instruction that they shall see that 
the whole of this work is carried out by 1918 or earlier, the instruction to set 
out certain guiding principles as to remedies and also grounds for exemption. 
As to exemptions, any recommendation for exemption signed by the local 
District Surveyor and two adjoining District Surveyors should be accepted 
ipso facto by the Building Act Committee as a prima facie case for exemption 
without further investigation or expense. 

(J) The energetic enforcement in 19 13 by legal proceedings of at least one 
notoriously bad case under Section q and one under Section 10 in each district 
as an earnest of the Council's intentions. 

(c) The formation of several Sub-Committees of three in the Building Act Com- 
mittee to sit weekly to accelerate the decisions requiring the Committee's 
attention under the 1905 Act, with the necessary strengthening of the Superin- 
tending Architect's personal staff and the staff of the Committee Clerk. 

(f) The immediate strengthening of the "Escape" branch in the Building Ait 

Department by five managing assistants, twenty senior assistants, twenty 
junior assistants, and twenty clerks, etc., all on the temporary establishment, 
the staff to work by areas, and each senior assistant to follow his own case from 
beginning to end, all modern mechanical equipment and facilities to he used to 
accelerate the work, including photography and mechanical copying instead of 
tracing. 

(g) The publication quarterly of a list of building owners who have complied with 
the Building Acts (Amendment) Act of 1905 and the addresses of the buildings 
that have been put in order. 

If the remedy be organised somewhat on these lines the Council will, in the f 
place, find that much of the necessarv work will be done by owners voluntarily v 
the given time-limit at their own dates and in a manner convenient to themselv s 
i.e., when doing their usual decorative and structural repairs. They will find 

' f 6 5 



CORRESPONDENCE. [CONCRETE] 

number of the owners will submit their own plans and suggestions. The Council will 

be rid of much of the work under seets. 10 to 12, which the district surveyors are quite 
capable of handling, and they will find their intentions to carry through this somewhat 
unpleasant duty of enforcing the Act of 1905 in an equitable and businesslike way will 
be appreciated and met in a proper spirit by the majority of building owners and their 
professional advisers. As to the cost that falls upon the building owm rs, they have 
already had seven years' time to accumulate the necessary funds. 

Given a procedure on these lines, the necessary alterations to existing buildings 
can be readily completed in five years, and the structural work will not be found to 
inconvenience the metropolis, as it is mainly internal and less in quantity than what 
has been done in London in several active building periods of lesser duration. 

There is, I feel sure, little that is unreasonable in my proposals as to the remedy 
oi the present grave scandal of unnecessary danger from fire, and I thus trust that 
what I suggest, or something equivalent, will be promptly carried into effect in the 
interests of the community. 

I am, dear Sir, 

Yours verv truly. 

Edwin O. Sachs 
Offices of the 

BRITISH FIRE PREVENTION COMMITTEE. 

S. Waterloo Place, London, 5.11'., 

December nth, igi 1. 



66 



B 



, CONSTIJUCTIONA 1 ] 
l KNOITM EER I NO — ? 



iVHVV BOOKS 



NEW BOOKS 

AT HOME AND ABROAD. 

A s/ior/ summary of some of the leading books ivhich have appeared during the last few months. 



"Artistic Bridge Design." By H. G. Tyrell. 

Chicago: The Myron C. Chirk Publishing Co, Price 
S3 net. 

A handbook consisting mainly of small 
illustrations and comments. There are 
242 figures and plates in the 287 pages. 

Mr. Thomas Hastings, the well-known 
architect of New York, contributes an in- 
troductory chapter on the general problem 
of the architectural character of bridge 
design, with some special references to 
the design prepared by his firm for the 
new Manhattan Bridge. The author's 
chapter headings deal with the Importance 
of Bridges, Reasons for Art in Bridges, 
Standards of Art in Bridges, Causes for 
Lack of Art and Special Features of 
Bridges before Principles of Design are 
discussed, and the Consideration of Steel 
Structures, Cantilevers, Metal Arches, 
Suspension and Masonry Bridges follows 
and complete the index. 

We venture to think that this order 
suggests that the relation between cause 
and effect — 'that is, between constructional 
cause and artistic effect — has not been suf- 
ficiently appreciated, and that the large 
and miscellaneous collection of small 
photographs and thumb-nail sketch eleva- 
tions need fuller analysis and some elimi- 
nation before the real " Causes for Lack 
of Art " in Bridge Design are laid bare. 
Mr. Tyrell, however, interestingly states 
his conclusions as follows : — 

" The reasons for lack of beauty in 
American bridges are as follows : 

1. Indifference of engineers and their 
lack of artistic training. 

2. Competition and commercialism, 
resulting in use of contractors' plans. 

3. Lack of co-operation from archi- 
tects. 

4. Absence of art standards for metal 
bridges. 

5. Haste in construction. 

6. Railroad bridges used as proto- 
types for others. 

7. Legal and financial hindrances. 

8. Inadequate material. 

q. L nsuitable and unsymmetrical 
location. 



10. Absence of State or Municipal 
supervision. 
" The Standards of Art in Bridges " 

proposed by the author are generally free 
and sound, but, we fear, insufficient to 
guide the student, while No. 4 begs the 
whole question. They are : 

1. Conformity with environment. 

2. Economic use of material. 

3. Exhibition of purpose and con- 
struction. 

4. Pleasing outline and proportions. 

5. Appropriate but limited use of 
ornament. 

It is to be regretted that opinion in the 
universe has become so mixed on the 
simplest problems of design, through the 
multiplication of facilities for the eco- 
nomical reproduction of photographs and 
sketches, and that the expensive careful- 
ness with which such an important subject 
should be treated has to be deemed 
luxurious ; students therefore have, in 
many subjects similar to that treated in 
this book, as best they can, to digest a 
crowd of imperfectly illustrated examples 
on quite insufficient information and 
wrestle doubtfully with insecure con- 
clusions. 

This handbook will not advance the 
serious study needed, and for the English 
student will not replace the pamphlet con- 
taining Mr. Husband's paper on the 
" /Esthetic Treatment of Bridge Struc- 
tures " read before the Institution of Civil 
Engineers in iqoi with the report of the 
important discussion in which some lead- 
ing architects took part which ensued 
during two meetings. The aesthetically- 
minded engineer would, we fear, be too 
simple to withstand his clients' thirst for 
sensations, while the practically-inclined 
artistic critic would scarcely carry con- 
viction of his sincerity to his audience. 
Bridge architecture remains still a test of 
natural characteristics; what we shall do 
next, who knows? Why not a simple 
concrete beam across the Thames? at 
once embodying all the primitive virtue 
of constructional efficiency at 
the pitfalls of art criticism. 



67 



INDUSTRIAL NOTES. 



[CONCRETE 



INDUSTRIAL NOTES. 

These pages have been reserved for the presentation of articles and notes on proprietary 
materials or systems of construction put forvjard by firms interested in their application. With 
the advent of methods of construction requiring considerable skill in design and supervision, 
many firms noivadays command the services of specialists "whose vieivs merit most careful 
attention. In these columns such vieivs ivill often be presented in favour of different 
specialities. They must be read as ex parte statements — iviih nvhich this journal is in no ivay 
associated, either for or against— but w would commend them to our readers as arguments by 
parties "who are as a rule thoroughly conversant ivith the particular industry -with vuhich they 
are associated. — ED* 



TRIANGLE MESH CONCRETE REINFORCEMENT. 

A form of reinforcement of American design has been brought to our notice by a 
recent report of the British Fire Prevention Committee, which report we reviewed in 
our last issue. It is a triangular wire mesh, and, though comparatively new to this 
country, is extensively used in America and other foreign countries. It i-^ particularly 
applicable to slabs and partitions, but is also commonly employed for columns and 
pipes of large diameter. 

It is made of hard drawn cold -teel wire with a tensile strength of 38 tons to the 
square inch and an elastic limit of 22 tons per square inch. There are no welds in any 




■■PIHHI 



Robinson & Mi ndy's Hi 11. ding, Rangoon, Burma. 



pari uf the fabric, and the process «>f drawing eliminates the possibility of Haws. It is 

'd a iruss form of construction, which provides an excellent mechanical and adhesive 
bond in the concrete, and reinforces in every direction. The cross-wires a-^ist the 

68 



1 



L. CONSTRUCTIONAL] 
' ENf.INKF.HlNO — J 



TRIANGLE MESH REINFORCEMENT. 



longitudinal members 
effective sectional area 



fcld 

can 




Hongkong Hotel, Ho> 



in resisting the tensional stresses, therebj increasing the 

and enabling the engineer to use a lighter material for carrying 

iven load. Being of the hinged-joint construction, the fabric is flexible, and mav be 

d on any longitudinal member without bending the cross-wires; consequently it 

>e made to assume various conformations withoul producing any initial str< 

_^_^^^___ The difficulty of 
^ maintaining equal 

spacing of bars is 
entirelj avoided, and 
the material can be 
laid by unskilled 
labour, It is supplied 
in continuous rolls up 
lo 300 ft. long, so that 
no material is v\ asti d 
by longitudinal laps ; 
architects and engi- 
neers can therefore 
readilv ensure thai 
the amount of rein- 
forcement t h e v 
specify is actually 
installed. 

As stated above, 
the material was sub- 
mitted to the British 
ngkong, china. Fire Prevention Com- 

mittee on July 24th, 
1912, and successfully passed their severest test, the calculated factor of safety being 
35. The following is an extract from their report : — 

Object of Test. 

To record the effect 
of a fire of three 
hours' duration, the 
temperatures to reach 
i,8oo° Fahr., bin not 
to exceed 2,000° 
Fahr., followed bv 
the application of 
water f r fi v e 
minutes, with a view 
to classification under 
" Full Protection " 
(Class B). 

Note. — The ana 
of the floor under 
investigation was 
to be at least 
200 ft. super. The 
floor was to be 
loaded with 280 lb. per square foot distributed. 

The area of the floor in this case was 334 ft. super., divided into three equal 
reinforced concrete bays, supported by four rolled steel beams; the beams had a 
span of 15 ft., and the bays measured 15 ft. by 7 ft. 5 in. centre to centre; ,the 
floor was 5 in. thick, and the depth of the beams below the underside of the 
floor was 14 in. 

The load was 280 lb. per square foot. The water was applii d for five mi 
from two branches. 

Note. — The time allowed for drying was thirty-four days (s 
centering was struck after twentv davs. 

69 







Hongkong Hotel. Hongk 



INDUSTRIAL NOTES. (CONCRETE 



Summary of Effe< i. 
At the expiration of ten minutes the floor began to deflect, and continued to do 

so until the end of the test, when a maximum deflection of 4A in. was registered. 

On the application of water the concrete to the soffit of the beams, where 
struck by the jet, was knocked off, exposing the reinforcement, or wirework, under 

the beams. 

The soffit of the floor was also eroded where struck by the jet, exposing the 

reinforcement. 

On the load being removed the upper surface of the flour showed various 

cracks. 

The permanent sel of the floor over the beams was about i in., and the 

permanent set of the bays between the beam- was about 2\ in. 
Neither fire, smoke, nor water passed through the floor. 
Classification " Full Protection " (Class B> was obtained. 

As an auxiliary test the floor was allowed to cool and the load removed. It was 
then reloaded, on the centre bay only, with a load of 5 cwt. per square foot, this bay 
being strutted. The deflections recorded wen as foil >\\ s : — 

Beam. Centre of Slab. Beam. 

Permanent set, July 31st, no load o'6 ... 2-4 ... 0-4 

Load of 5 cwt. per sq. ft., August 15th ... rq ... 4 - 1 ... 17 

Deflection due to additional load 1*3 ... r~ ... 1-3 

The above readings were taken by a dumpy level. It will therefore be seen that the 
deflections of the slab itself, carrying a load of 5 cwt. per square foot, and after being 
subjected to the previous severe fire and load test, was only vj minus i - 3=o*4 inches. 
This test, which we believe to be unique in this country, should prove interesting to 
those who are concerned with the safety of reinforced concrete buildings after having 
been subjected to a severe fire. 

Similar tests to the above have also been made under the supervision of the officials 
of the Bureau of Buildings of New York City. In this case the ends of the beams were 
framed as they would actually be in a building of American design. The result of these 
tests showed less deflection than those recorded above. The makers strongly recom- 
mend, and apparently with some justification, the stiffening of the ends of all beams, 
and it would appear that English architects might follow out this practice to advantage. 

The accompanying illustrations show this mesh as it was actually installed in a 
building in Rangoon, Burmah, and in the Hongkong Hotel, China. The latter shows 
the work being performed by coolie labour. 



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70 



g 



.OONSTEUCTIONAIJ 

ENfjlMLEIJl NG J 



A MODEL FARMSTEAD. 



POPULAR USES. 



Under this heading it is proposed from time to time to present particu'ars of the more 
popular uses to ivhich concrete and reinforced concrete can be put, as, for instance, in the 
construction of houses, cottages and farm buildings. — ED. 



A MODEL FARMSTEAD AT BONSAUVEUR CONVENT, DUNGARVAN, 

IRELAND. 

]n the present article we present some interesting particulars and illustrations of some 
new farm buildings of Winget Concrete blocks erected for the Bonsauveur Convent at 
Carriglea, Dungarvan, Ireland. 

Some of the buildings shown here are of one storey and are built with q-in. hollow 
concrete blocks, whereas the two-storey buildings, comprising stables, coach-house, 
laundry and steward's house, have the walls of the ground floor storey built on the 
cavity system with a -tA-in. outer leaf and Q-in. solid inner leaf, bonded together with 




Fig. 1. Front Elevation, Main Building. 
Model Farmstead, Bonsauveur Convent, Dungarvan, Ireland. 



galvanized wall ties, the upper storey being built with q-in. hollow concrete blocks. 
Breeze concrete slabs 2 in. thick form the internal partition walls and prove very 
effective, being light yet solid and occupy very little space. The aggregate for blocks 
was pit gravel passed through a f-in, screen, mixed in the proportion of five o\ gravel 
to one of Portland cement. About 16,000 blocks were used in the erection of this 
model farmstead. 

Our first illustration shows the front elevation to the main building with the 
principal entrance under the archway. This building contains the - 
coach-house, stables, and laundry, and measures 150 ft. by 30 ft. and 26 ft. I 
Fig. 4 gives an excellent view of the fold-yard, showing the implemi n 



POPULAR USES. 



{CONCRE TE! 



IL— - I 



I 



3 



r J » 






11 F 




Fig. 2. Back of Main Building 




FU. 3. Interior of Fold-Yard. 
Model Farmstead, Boksauveur Convent. Dungarvan, Ireland 



f if. CX)NSTBlKTIONAI. , | 
( yi ENGINEERING — J 



A MODEL FARMSTEAD. 





s z 

■s. Q 




■ 



piggeries, and back en- 
trance. There is also 
an infirmary for sick 
cattle, which, with the 
piggeries, measures 1 50 
ft: by is ft. 

Eig. 2 shows 1I1 ; 
back of the main 
building. 

'i he laundry to 
which referen< e has 
been made comprise s, 
in addition to the laun- 
dry proper, a drying 
room, an ironing-room, 
and a mangling-room. 

T h e illustrate n 
Fig. 3 shows the in- 
terior of the fold-yard, 
with the hay-sheds and 
lofts above same. 

Special attention is 
called to the fact that 
most of the external 
walls of these buildings 
are built on the continu- 
ous cavity system, of 
which mention has been 
made earlier in the ar- 
ticle This system en- 
sures a perfectly dry 
building, no matter 
what atmospheric con- 
ditions prevail, and 
further it is claimed 
that it is a most effec- 
tive insulation against 
changes of temperature 
inside the building, in- 
asmuch as it prevents 
condensation on the in- 
side of the walls and an 
increase of temperatur 
in hot weather or a 
lowering of the tempera- 
ture in cold weather. 
These points may be 
consider* d of import- 
ance, and l hey apply 
equally to the cold, raw 
climates 1 f the north 
and to the t r op i c a 1 
countries. 

The entire blocks 
and slabs were made on 
" Winget " mac' 
and th 

Messrs. John 
and Son, ' v 



memoranda. 



[CONCRETE ] 




Memoranda and Nevus Items are presented under this heading, -with occasional editorial 
comment. Authentic netvs "vill te -welcome. — ED. 



The Society of Engineers (incorporated).— At a meeting of the Society of 
Engineers (Incorporated) held on December 2nd, Mr. Percy J. Waldram, F.S.I., 
M.C.I., read a paper on " Test Deflections in Reinforced Concrete," a subject which, 
he stated, was one requiring the closer attention of engineers before a standard of 
deflection was fixed by the proposed L.C.C. regulations; a standard which might or 
might not be correct or even safe. 

The stiffness of a beam was no criterion of its strength unless due regard w< re 
paid to the factors of depth and fibre stiffness. The small deflections of reinforced 
concrete beams were sometimes quoted as evidence of the strength of the material, but 
it was seldom noted that the deflections were small because the greatest loads placed on 
reinforced concrete were very much less than those commonly used upon wood or steel. 
Reinforced concrete was a much weaker material than steel or ordinary fir, for beams 
of equal size. 

The draft regulations for reinforced concrete, compiled and approved by the 
London County Council, were submitted to the principal architectural and engineering 
institutions for criticism, and published in the Minutes of the Council. The author had 
been consulted in a case where the parties had agreed to work to the regulations as 
published, when the opportunity of applying them to the problem of a somewhat 
difficult design gave disquieting results. For instance, the clauses determining the 
strength of columns were quite unworkable, and those relating to deflection proved 
positively dangerous, as was shown by examples. 

A standard of deflection suggested by the author was referred to, but he pointed 
out that the effect of end fixing was not yet fully determined, and that it was impos- 
sible to legislate on an uncertain basis. The minute range of the deflections made it 
all the more necessary to use the greatest care in fixing a standard. 

Reference was then made to the calculations necessary to determine the strength 
of reinforced concrete beams, and a number of formula? were given, with explanatory 
notes. The application of these to well-known tests was shown by a series of eight 
diagrams, and particular attention was directed to one in which the conditions were 
such as were generally supposed to make the calculations almost impossible, on 
account of their intricacy. The author, however, showed a method which he considered 
would very much facilitate the problem. 

Reinforced Concrete for Hypochlorite Solution Tanks. — In a recent number 
of the Concrete Age a -diort article has appeared bv Dr. Walter M. Cross, U.S.A., on 
the above subject. An experimental installation of the hypochlorite process for the 
approximate sterilization of the entire municipal water supply of Kansas City, Mo., 
proved so very successful in every way that the Fire and Water Foard of Kansas 
decided tn erect a permanent building and apparatus for the purification process of the 
water supply. 

A separate building was constructed f i >r storing, handling, and making the solution 
of hypochlorite for mixing with the sedimented water. The apparatus for the handling 
of the hypochlorite and the supports for it are of reinforced concrete. It was found 
that no other material was so well suited for the purpose. 

Thi' basemenl of the building is used for storage, the main floor houses the dilution 

"4 



JlJIIIIlgg MEMORANDA. 



tanks and feeding devices, while the floor above is occupied mainly by the tank for thi 
hypochlorite, in which it is reduced to a paste of creamy consistency before being 

delivered to the dilution tanks below. This concrete tank is 3 ft. in diameter and 4 ft. 
high, and is provided with a strung device carrying two heavy rollers placed horizontally 
at its lower end. 

There are pipes leading from this tank to the dilution tanks below. These dilution 
tanks are hexagonal in form and are 9 ft. in maximum diameter and 7 ft. high. The 
dilution tanks rest on supports high enough to permit of the use of a gravity feed to 
the orifice box, which is on the floor of the room housing the big tanks. The writer 
concludes by saying that reinforced concrete is now everywhere employed in the United 
States in the construction of all permanent apparatus where hypochlorite is emploved 
for mixing with the water to be purified. 

Concrete versus Wooden Poles.— According to the Electrical World, the Carnegie 
Steel Co. recently conducted tests on reinforced concrete poles at its South Sharon 
(Pa.) plant, for the purpose of determining the relative cost and strength of com :ri te 
as compared with wood. The poles tested were 32 ft. long, 10 in. square at the butt 
and 6 in. square at the top. The corners were bevelled and iron steps bent up | in. 
were inserted in the forms before the concrete was poured. The mixture employed 
consisted of 1 part of cement, 2 parts of sand passing a 5-in. screen, and 4 
parts of crushed limestone passing a f-in. screen but retained on a |-in. screen. 
Each pole required about a barrel of cement, i yard of sand, and i yard of stone. 
The reinforcement comprised four groups of twisted rods at the corners, placed 
not less than ^ in. from the surface. Each group was made up of one h-'m. rod 32 ft. 
long, two i-in. rods 24ft. long, and two -fV-in. rods 16 ft. long. The reinforcement was 
thus proportioned to the decreasing stress toward the top of the pole. Sheet-steel 
separators held the reinforcement in place and were cut away to avoid breaking the 
continuity of the concrete above and below the separator. The forms used consisted of 
an upper and a lower section held together by bolts, the lower being a single piece, 
while the upper was made up of a series of units beneath which the concrete was 
forced. Each pole weighed about 2,500 lb., or approximately five times as much as a 
wooden pole of the same length. The tests were conducted with two concrete poles and 
a 32 ft. chestnut pole under the same conditions. It was found that the wooden pole 
showed practically the same deflection as the poles of concrete up to 2,000 lb., the load 
being applied at right angles to the pole and at the top. The deformation at 2,000 lb. 
amounted to 25^ in., this loading being far greater than could ever be experienced with 
the poles in actual use. For deflections of less than 15 in. the concrete pole showed no 
permanent set. A test to destruction was carried out on one of the poles, and failure 
resulted at the point where the 24 ft. reinforcement rods ended, the concrete being 
crushed for about 3 ft. above and below the break. The results obtained showed that 
the cost of manufacture of such poles should be from 30s. to £2, as against 16s. to 
£1, the price of a wooden pole. The cost of wooden poles is thus from one-half to 
two-thirds that of the concrete poles, and their life ranges from a minimum of ten 
years to a maximum of twenty years, whereas the life of a concrete pole is considered 
ro be practicallv unlimited. Moreover, the concrete poles require no painting. 

New Stores at The Camber. — Some new stores are to be erected for the Ports- 
mouth Camber and Docks Committee, and the buildings are to be of reinforced 
concrete. The contract for the work was put out to tender, and the tender of Messrs. 
McLaughlin Co., which was the lowest, was accepted. 

Portland Cement for Roofing.— A cheap and durable fire-resisting roofing is 
made in France with asbestos and Portland cement, in the proportion of one-fifth of 
asbestos fibre, one-fifth asbestos powder, and three-fifths Portland cement. The 
mortar, which must be carefully mixed, is pressed with the trowel into wooden moulds 
about 2 ft. square and one-fifth of an inch thick. These slabs, when perfectly sel 
used in the same way as slates and nailed to the woodwork of the roof. This k 
roofing, which is very light and durable, is said to be very suitable for sheds 
buildings. — Sanitary Record. 

Reinforced Concrete Pillar Boxes.— It is reported that the cast-iron pill; 
in New Zealand are to be replaced by some made of reinforced concrete, a 
shown that these boxes are stronger and lighter than the iron ones 
siderablv less. 

75 



MEMORANDA, 



[CONCRET E 



How to Patch a Concrete Floor. — When a cement floor surface begins to 

wear it is often desirable to patch it. Mr. Leonard C. Wason, presiden-1 <>t the 

Aberthaw Con- 
st r u c linn Co., 
Boston, in a recenl 
paper states the 
right way and the 
wrong way. 

The W r on g 
Way. — Commonly 
a sand and cemenl 
mortar is made, 
some cutting i> 
done, and the mor- 
tar is put in and 
scrub!).:! with a 
trowel until 
smooth. It is then 
covered up for a 
while. If the con- 
crete under t he 
patch is left dry it 
soaks up the water 
of the mortar. As 
a result, the mortar 
does not set. If 
the room is dry or 
hot, the surface of 
the patch dries out 
for the same reason 
it does not set. If 
the concrete under 
the patch, is dusty, 
the patch does not 
adhere to the 
concrete. If the 
materials in the 
mortar are not suit- 
able, naturally the 
patch wears badlv, ' 
particularly as it is 
obviously located at 
a point of severe 
wear. 

The Right 
Way. — Cut down 
the worn place at 
least i| in. This 
cutting should be 
carried into t h e 
strong unbroken 
concrete and the 
edges should be 
cleanly undercut. 
The bottom nf the cu1 should then be swept out, clean-blown out with compressed air 
or a pair of bellows, if available, then thoroughly wetted and scrubbed with a broom. 
h. this way small loose particles of broken material which the chisel has driven into the 
surface are removed. A groul made of pure cement and water about the consistenc} ol 
thin cream should be scrubbed into the pore-, with a broom or brush, both al the 
bottom and sides of the cut. Following this a stiffer grout, about the consistencj ol 

76 




y. CONSTPUCTlONAlJ 



MEMORANDA 



soft putty, should be thoroughly compressed and worked into the surface which has 
already been spread with grout. Finally, before the groul is sel a morta ol one 

part cement to one pari crushed stone or gravel, consisting of graded sizes from J in. 
down to the smallest, excluding dust, should be thoroughly mixed and put in place, 
then floated to a proper surface. Cover with we1 bagging, wel sand, sawdust, or other 







™E ASSOCIATE 



PORTLAND a 



- 







The Associated Portland Cement Manufacturers' Stand, Agricultorai 
Society's Show, Domcaster. 

available material. All trucking should be kept off and the surface ken: 
wet for at least one week or ten days. 

If a particularly hard surface is required, a few nails are sometimes mix' I 
mortar and other nails stuck into the surface when the patch is fini ' s will 

produce a surface which is extremely hard and durable. 




CONSTRUCTIONAL 



CONCRETED 




"Simplex" Steel Sheet Piling 



(Patent) 




L 

22 lbs, per super foot when interlocked 

Rolled Sections 8 ins. wide, of symmetrical shape 
and strong interlock. Narrow units for easy 
handling. Watertight owing to large interlock. 

CAN BE DRIVEN WITH HAND MAUL. 

Stocked in following lengths for dispatch at few hours' notice : — 
6, 8, 10, 12, 14, 16, 18, 20, 24, 28, 32 feet. 



On hire only for United Kingdom unless for 
permanent work. 

SOLD OUTRIGHT FOR ABROAD. 



Note— FOR HEAVY WORK OUR UNIVERSAL JOIST 
PILING SHOULD BE USED. 

All particulars from 

THE BRITISH STEEL PILING C° 

Dock House, Billiter Street 

London, E.G. 

Telephone 

i a i a k Telegrams 

1414 Avenue * 

1414 Central " Gramerey, London" 



78 Please mention this Journal "when -writim). 



E 



(.'ON.STPUlTIONALl 
ENC.IMEE.KINC, — 1 



MEMORANDA, 



TRADE NOTICES. 
Portland Cement at the Agricultural Society's Show, Doncaster.— W^hors to 

the Royal Agricultural Society's Show at Doncaster had the possibilities of the use 
of concrete on 1 1 1< • estate and farm placed before them in a very striking manner a( 
the stand of the Associated Portland Cement Manufacturers (1900), Ltd. Following 
out the educational policy which this company inaugurated at the previous year's Show 
at Norwich, they had a very large stand at which were displayed (for exhibition only 
and not for sale) all kinds of articles required for use on estates and farms. The rapid 
increase in the uses to which this material is being put was well illustrated by the fact 
that it was found necessary to have a stand exactly double the size of that at Norwich. 




^— - » HFan OFF 





The Associated Portland Cement Manufacturers' Stand, Agricultural 
Society's Show, Doncaster. 

There were displayed numerous reinforced concrete articles, such as rectangular 
and circular cattle troughs, hog troughs, chicken troughs, roofing tiles, flooring tiles, 
fence posts, and gate posts, and the moulds in which they were made. Many of these 
were of a similar character to those previously exhibited, except that parts were left 
unfinished so as to leave some of the ironwork exposed, thus showing the method of 
reinforcement and adding much to the interest of the exhibit. 

The stand was surrounded on all four sides with various types of concrete fencing, 
and at the front of the stand, immediately behind a pair of field gates hung upon 
large concrete posts, was a large concrete facia, on one side of which was the company's 
name in raised letters, and on the other panels illustrating different types of surface 
finish. Looking at this, one could quite realise that concrete name plates and street 
signs might be used to great advantage, as they are practically indestructible and, above 
all, cost nothing for maintenance. 

There were panels of " scrubbed concrete " on the other sides of the stand. The 
method for obtaining these results is very simple. As soon as the concrete is set (usually 
after about twenty-four hours) the side of the form is removed, exposing the surface 
of the concrete, which is then scrubbed with an ordinary scrubbing-brush to take off 
the film of cement and expose the aggregate. The use of various kinds of aggregate 
renders it possible to obtain a large variety of pleasing finishes in this way. 

A section of a concrete cow stall was shown which created considerable interest, 
and no one concerned with the welfare of cattle could fail to be struck by the admirable 
hygienic and sanitary properties of such construction. 

A lean-to roof partly covered with the concrete and asbestos " Poilite " tile 
manufactured by Messrs. Bells Asbestos Co. and partly with ordinary slate 11 
a saving of nearlv 75 per cent, of weight by using " Poilite" roofing: the w 
given being " Poilite " 21 lb., and Welsh slates 80 lb. per yard super. 

The Associated Portland Cement Company distributed at the stand a 
enlarged and improved edition of their valuable pamphlet, entitled "Concrete on the 
Estate and Farm," copies of which, we understand, they will be please- 
anyone interested upon receipt of request addressed to Portland Hoi me, 

E.C. 79 



MEMORANDA. [CONCRETE) 



New Reinforced Concrete Loading Pier at Southend on-Sea. --('<>n-uu< tion 
work has commenced for the new loading pier which the Corporation <>l Southend-on- 

Sea has decided to erect under the superintendence of Mr. Ern<'st J. Elford, M.I.C.E., 
the Borough Engineer. The total length of the pier will be 600 ft., and it has been 
designed for a working load of 5 cwt. per sq. ft. The whole of the work will be 
executed on tin- "Piketty" system of reinforced concrete. Mr. T. W. Pedrette, 

Enfield, N., is the contractor. "The contract is for ^11,000. The Borough Engineer 
selected and recommended the adoption of the " Piketty " system after receiving 

gns in open competition from other firms of reinforced concrete specialists. 

The Armoured Tubular Flooring Co., Ltd. — H.^l. Office of Works have recently 
entrusted to the Armoured Tubular Flooring Co. certain works in connection with 
Hertford House, Manchester Square, where the valuable Wallace Collection is housed. 
The work, which has been carried out to make the building more fire-resisting, includes 
the reconstruction of the upper portion of the right wing. The old roof has been 
removed and the existing wooden floors have been taken out by the contractors, Messrs. 
Dove Bros., and a new fire-resisting floor has been installed on the armoured tubular 
system, also some flat roofs adjoining. The whole of the work has been carried out 
without any centering whatever. We hope in a subsequent issue to deal with this work 
more full v. 



MISCELLANEOUS 

Rate —6 lines for under), 5s : each additional line, lOd. Remit with order, 

/^LERK OF WORKS— To supervise and CONCRETE BOOKS at GREAT REDUC- 

( . , , c e .„■-., ; n in^; 5 ^ — ' TIONS. — New Books at 25 per cent, discount. 

V^set out constructional work cf a fac ory in India, Books on Concrete Engine ering. Building Construction, 

embracing concrete work, erection of heavy milling Technical and all other subjects supplied. Sent on Ap- 

machinery, engines, iron roofs and buildings and to proval. State wants. Send for Lists. Books purchased. — 

carry out, if necessary, any small jobs such as founda- W. & G. Fovle, 121 Charing Cross Road. London. W.C . 

ti^ns for columns, engines, machines, shafting, etc., T^NGINEER FOR INDIA. — Wanted in 

laying in surface drainage, concrete floors or small iron -1— 'New Year, on a four years' agreement, a good 

sheds, which were inconvenient to sublet. Job will last man well experienced in ferro-concrete work, drainage, 

. and general constructional work for a firm of contrac- 

about nine months, and if he proves himself active. tors Able to work as required, either in office or outside 

energetic and useful, might lead to a permanency or work, and make himself energetic and generally useful, 

transfer to other similar work. Must promise to learn Hindustani. 

Apply by letter to Edward Williams, 11 Derby Apply by letter, stating experience age and salary 

, * , , . , . , . required to Edward Williams. 11 Derby Road, 

Road, Tolworth, Surrey, stating salary asked, when Tolworth, Surrey, who will also supply suitable appli- 

dispngaged, experience and references. cants with fuller details. 



BRITISH IMPROVED CONSTRUCTION CO. 

Telephone: 4067 Victoria. LTD. Telegrams: " Biconcrete, Vic. London." 

"BIC " 
47 VICTORIA STREET, WESTMINSTER, S.W. 



Manufacturers of all kinds of 

Concrete Constructional Materials 

Plain or Reinforced) 

Including PIPES, PARTITION AND PAVING 
SLABS, SLEEPERS, STANDARDS & POWER 
TRANSMISSION POLES, HOLLOW BEAMS 
AND FLOORS, FENCING POSTS, etc, etc., 
by the well-known "JAGGER" PROCESS. 

Engineers and Contractors Own Designs carried out to order 

SPECIALITY. — Reinforced Concrete Pipes for High Pressures, abso- 
lutely Impermeable. Our Concrete weighs 156 lbs. per cubic foot. 



80 



Plejse ment'or. this Journal when iimting. 



[ CONCRETE 

AND 

CONSTRUCTIONAL ENGINEERING 



Volume VIII. No. 1. London, February, 1913. 

EDITORIAL NOTES. 



THE ASSOUAN DAM. 

The completion of the Assouan Dam — one of those great achievements 
of British thought and work which will materially benefit many thousands of 
human beings, and stand for many centuries as a landmark of British enterprise 
— was accorded somewhat less space in the public Press of this country than 
is given to a fashionable fancy dress ball, and certainly much less than to some 
notorious law case. Another feature regarding the reports of the completion 
of this work was that they seemed studiously to avoid giving the slightest 
tribute or praise to that splendid band of technical workers, both skilled engineers 
and foremen, who, by forethought, energy and diligence, not only played an 
all-important part in the earning out of this great scheme, but to whom must be 
attributed the highest praise for precision combined with smartness, under 
circumstances that were frequently exceedingly trying. 

We have dealt with the Assouan Dam at considerable length in our issue 
of April, 191 1, which was illustrated with the most perfect photographs avail- 
able, and we do not hesitate to reprint our frontispiece of that issue, as a 
reminder of the extent and grandeur of this work. It is, therefore, unnecessary 
to recapitulate the numerous figures presented with our article as to the size 
and effective value of the undertaking. 

Only in one direction do we again wish to emphasise some views expressed 
by us on the occasion of that article — viz., in respect of the submersion of the 
Temple of Philae. We would repeat that this temple is one of many ruins 
situated between Cairo and Wadihalfa, and although ancient temples as a whole 
are of the greatest possible interest, the single specimen is a mere entity. 
Whether one or a dozen of the ruins disappear to-day is merely a matter of 
sentimental regret. We have all the historical records we require, and the 
practical loss would be nil, for there is no utility in the ruins, except, perhaps, 
as some slight attraction to tourist money to Upper Egypt. 

It is well indeed that this temple has not been allowed to stand in the way 
of the development of Egypt; to have permitted it to act as a deterrent would 
have been as unreasonable as it would have been inhuman. Humanity requires 
that our knowledge, skill and means be applied to the improvement of mankind. 
The lot of the Egyptian is vastly improved by the Assouan Dam. With the 
increased prosperity of Egypt, funds become available for the better 
and sanitation of that country, for the reduction of eye-diseases, lor < 
education, and for general civilisation, and it is absurd to ex 
benefits should be prevented or retarded by egoistic art-lovers, who, i 
most part, know little and care less for Egypt. 

b Si 



THE ASSOUAN DAM. EONCBETE) 

] he great Assouan Dam Is therefore not only an immense work realised, but 
a distinct victory over morbid sentimentalism in the matter of second-rate ruins, 
and shows that common-sense is wanted where hysterical hypocrisy so frequently 
and unfortunately gains its way. 

One last word. We see that the primary worker in respect of the success- 
ful completion of the Assouan Dam — Mr. Murdoch Macdonald, C.M.G. — has 
now been appointed to the hig'hesi office available in the Egyptian Ministry of 
Public Works. We congratulate him upon this well-earned compliment ; we 
also congratulate Lord Kitchener upon putting- the right man in the right place. 
When some day the true history of the Assouan Dam comes to be written, 
it will easily be seen that the influence of this worker on the spot has been of 
even greater importance to the undertaking than that of others who have 
perhaps figured more conspicuously in the public Press, and it is to be regretted 
that some of our greatest works and workers are almost invariably not accorded 
that credit which is due to them in great engineering enterprises. 

AN ACTIVE CONCRETE INSTITUTE. 
We have received particulars of the impending annual meeting of the 
German Beton-Verein which is to be held at Berlin on February 13th and 14th, 
and we are struck by the excellence of their programme. 

Apart from the usual annual report, there will be a special report on the 
Testing Commission of this body, which has done such valuable research work 
in the past. There will be a report on the co-operation of the Society in the 
Building Exhibition to be held at Leipzig next summer, and a similar report on 
the question of Arbitration as applicable to the concrete and reinforced concrete 
industry. Two of the leading authorities on research work in German}- are 
presenting lectures — viz., Professor Rudeloff on "Tests with Columns," and 
Professor Gary as to the " Rusting of Metal and Brickwork." Dr. Trauer is 
presenting a paper on a gigantic auditorium of reinforced concrete construction 
which is at present being erected at Breslau. Mr. Christiani reports on 
"Reinforced Concrete Quays," whilst four other members are presenting 
papers on notable buildings carried out during the past year. Besides this, 
three precis will be presented, one on " Failures in Building Construction," a 
second on the " Effect of Earthquakes on Concrete and Reinforced Work," and 
a third on the " Effect of Explosions on Concrete." 

Surely this is a remarkable and eminently interesting programme of work, 
which is of the greatest possible credit to the Society in question, and a pro- 
gramme of this description is not only highly instructive and beneficial to the 
members of this Institute, but raises its work to a position where it cannot fail 
to be appreciated by all concerned, and the public authorities in particular. 

Our own Concrete Institute would do well to take a leaf out of the book 
of their allied Institute's Berlin programme. 

REINFORCED CONCRETE FAILURES. 

WHEN the Concrete Institute had been fairly started, some four or five years 
back, one of the first pieces of work suggested as a safeguard to the professi cis 
and industries alike- suggested by their first chairman -was the careful 
investigation of the reinforced concrete failures, as affording some of the best 
practical lessons as to precautions to be observed and errors to be avoided. 
82 



&%£$$£$£$ REINFORCED CONCRETE FAILURES. 

But there has always appeared to be some diffidence as to getting to work- realh 
seriously on this all-importani subject, this being mainly due to thai extra- 
ordinary fear ol responsibility which prevails among professional men who 
cannol realise that a statement of fad in the public interest, properly and 
conscientiously put, can never be a libel, and partly owing to a certain fear 
among those of the members of the Institute who are concerned with the 
specialist firms, that some failures of theirs mighl come under view to tin 
detriment of their standing. Recently, however, a small sub-committee has 
been formed to go into the matter, but certainly up to die present we have heard 
of no case ol systematic investigation, nor have we seen any programme of how 
the inquiries are to be conducted. 

England has fortunately been fairly free from serious accidents in rein- 
forced concrete work, although there have been several notable ones which do 
little credit to those primarily concerned. Fortunately, however, we have not 
come across any accidents of this kind which can be attributed directly to any- 
thing that might be detrimental to the interest of reinforced concrete as a 
whole, inasmuch as none of these accidents have so far shown that reinforced 
concrete, if properly designed and properly executed bv competent and 
responsible people, is in any way more dangerous than any other form of 
building construction properly designed and properly executed. The failures 
have been largely due to negligence, stupidity, or sheer scamping. 

There are two words of warning on the matter of failures which we would 
like to g'ive. 

The first is to the builder or contractor. It is to the effect that it is unwise 
to handle reinforced concrete in any form, unless to the design and specifications 
of experienced men, and unless carried out honestly by experienced artisans. 
There is no form of building construction that is more dangerous when sub- 
jected to false economy or dishonesty than reinforced concrete construction. 

The second is addressed to the reinforced concrete specialist who combines 
designing with contracting, and that is, that the present competition to obtain 
work at entirely unsuitable prices must be disastrous to the development of the 
work they have in hand, and if the}' do not have immediate disasters actually 
during the course oi construction, the manner in which they are -often " cutting 
tilings fine " in design and quality of materials must obviouslv result in 
prospective failures when the effect of their scamping becomes apparent 'up in 
the structures they have put up when subjected to the strain of actual usage. 

It is to the interest of all those industrially concerned to stop this 
scamping- in design and poor workmanship promptly, even if they have to be 
satisfied with a lesser return for their work, for if failures through had design 
or scamping increase, reinforced concrete — which has been adopted with 
reluctance in this country — will suddenly become as unpopular as certain other 
forms of buildings have become, and those who wish to earn their living thereby 
will have to find fresh fields, instead of sensibly developing their present one. 

The professions and industries concerned must further plainly face 
actuality of failures, investigate the causes thereof, and publicly crw 
who are responsible for them, if they wish the reinforced concrete in 
flourish. 

r. 2 8 3 




8+ 



. ENG1NLE.MNG-— : 



REINFORCED CONCRETE RUBBER WORKSHOP. 




^m-||:^r' ; ;^; extension of works | 

-SIEMENS BROS. & CO., | 
WOOLWICH. 




By F. SOU THEY, A.M.Inst.CE. 



The following particulars of the extension of Messrs. Siemens' s works may not le 
•without interest to those contemplating aiditions or alterations to similar buildings. —ED. 



In the new buildings recently erected for Messrs. Siemens Bros. <v Co., at 

Woolwich, concrete and reinforced concrete have been used on a large scale. 
Concrete has been used exclusively in the foundations and reinforced concrete 
in live floors, roofs, columns, staircases, and lintels in the superstructure. The 
walls are in brickwork, with piers to take the load on the floors and brick 
panelling- and window openings between. This method of construction was 
adopted in the case of two large and one smaller building, and a short descrip 
tion of each, with special reference to the concrete work, may not be without 
interest. 

NEW RUBBER WORKSHOP. 

This building, containing a capacity of nearly two million cubic feet, is in 
plan composed of two wings or blocks, forming at their junction an angle of 
O-ji degrees. The south block is 320 ft. in length and the west block 202 ft. 
in length, measured from the external point of intersection of outer walls. The 
uniform width between external faces of piers is 50 ft. 9 in. There are six 
floors, including the basement, giving a total floor area of just over three acres. 
The height from basement floor to mean roof level is 79 ft. 

The building is supported on 153 concrete piers founded on sand. The 
piers are 5 ft. by 3 ft. b in. under walls, 5 ft. by 4 ft. under columns, and 
5 ft. by 5 ft. at corners. They varied in depth from 7 ft. to 14 ft. 9 in. below 
basement floor level, which is itself 7 ft. 6 in. below general ground 
level. The base of each pier was extended on all sides by under- 
cutting in order that the distributed load on the sand should not exceed three 
tons per square foot. 3,000 cub. yds. of concrete were placed in piers and 
trenches, the concrete (as is the case with the other buildings) being com- 
posed of 1 part of Portland cement to 6 parts of Thames ballast with a suitable 
proportion of " plums." Gravity concrete mixers were used for the bulk ot the 
foundation work. 

A single row of 2<S columns along the major axis of the south block 
12 in the west block divides the width into two equal spans of 22 ft. 9 in 
columns carry transverse beams, there being no secondary beam 
one end bay of longer span. 

The columns on each Hour are uniform in size; liny are 2 



F. SOUTHEY. 



(CQNCREX FJ 




New Rubber Workshop, Shuttering for Beams and Columns 
Extension of Messrs. Siemens Bros.' Works, Woolwich. 




86 



New Rubber Workshop, showing Centering for Ground Floor. 
1 oi Messrs, Siemens Bros.' Works, Woolwich. 



n 



, , coTsyrpucTioNA : .1 

V ENGINEERING — .', 



REINFORCED CONCRETE RUBBER WORKSHOP. 




_p£__:i_l#. 






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RjQNCBEXFj 



under ground floor, [8 in. by iS in. under first floor, ;m<l 10 in., 1 5, in., 12 in. 
and 10 in. square under second, third, fourth, and roof respectively. They are 
chamfered at the corners. 

The south block columns carrying the ground floor are reinforced with eight 
rib liars, four |-in. set at each angle, and four intermediate of f-in. section, while 
those in the west block are qua! in number but of larger sectional area, being 
respectively four [-in. and four f-in., the heavier bars being placed at the corners 
in every case. This increase in the case of the west block as compared with the 
south on account of the extra load carried continues upwards. Columns under first 
and second floors have also eight vertical rib liars, but those under third, fourth 




New Rubber Workshop, Third Floor. 
Extension o" Messrs. Siemens Bros.' Works, Woolwich. 



and roof have only four. The sectional area of steel, as well as the size of column, 
diminishes as the point loads decrease, and the columns under roof con- 
tain four A-in. rib bars only. All columns are bound with &-in. mild steel wire ties 
up to third floor level at 12-in. centres, under fourth floor at 10-in. centres, and 
the roof columns at 9-iri. ((litres. These binders are threefold, square over all, 
and bracing opposite intermediate verticals. The beams are generally 20 in. by 
10 in., measuring i_| in. In [0 in. below the 6-in. slab. They are rein- 
forced with i f-in trussed and rib bars of varying size to complete the required 
sectional area, which are cranked up lor shear and carried over columns for con- 
tinuity. On all the floors and roof 4 , -in. by if-in. K.S.Js. are cast in the 

88 



REINFORCED CONCRETE RUBBER WORKSHOP. 

' H ''." ns ' * , ; r bottom ? a "? € Projecting i in. below the soffit lor shaft and machinery 

; Xm - ; th6SC ar V! Cd ,n hv means " r hairpin stirrups passed through holes in 
the upper pari oi the \v< b. 

The slabs are uniformly 6 in. thick and reinforced with rib bars of , aryin* 
S1Z€ ' S P aced from S in - t0 [2 i]1 - between centres, the bars of each slab being 
cranked up over the beams for shear and continuity, while end slabs have 
inverted trussed bars placed on iS-in. centres in the top to assist compression. 
I he rool slab has an over-sail forming a cornice reinforced with |-in rib bars 
spaced 2 ft. apart, and the whole surface is covered with ruberoid 

The following gives the calculated superloads on the respective Hoars in 
the west block, where the maximum loading occurs :— Ground and second il ,ors 




New Offices and Store, showing Floor in Course of Construction. 
Extension of Messrs. Siemens Bros.' Works, Woolwich. 

3 cwt. per sq. ft. ; first floor, i£ cwt. ; third floor 2 cwt. ; and fourth floor 1 cwt. 
per sq. ft. 

Ihe two internal staircases are in reinforced concrete with landings and 
risers carried on main and stringer beams reinforced with trussed bars. 

The concrete in the reinforced work was gauged 1 part of Portland a man, 
2 parts of clean sand, and 4 parts of Thames ballast crushed to pass a 
mesh. For the mixing of this two concrete mixers of the Swiss type were 
used. About 3,500 cub. yds. of concrete and 230 tons of steel reinfon 
were used in the superstructure. 

On the roof are placed two gcarhouses in connection with the \ 
the hits. In each block an external iron staircase is provided foi 
of emergency. 



F. southey. [CONCRETE] 

NEW OFFICES AND STORE. 

This is :i building of five storeys, 90 ft. in length by 40 ft. in width, with 
an annexe and lean-to roof 25 ft. wide running- the whole length of the west 
side. 

The main building is supported on 18 concrete piers founded on sand. 
These piers varied in depth from 22 ft. o in. to 28 ft. below ground level. The 
central row of six piers (each 5 ft. by 3 ft.) supports columns that divide the 
internal width of 3G ft. 6 in. into two unequal bays of 22 ft. and 
14 ft. o in. respectively. The piers under the east wall (on which 
side is the longer span) are 5 ft. 3 in. by 3 ft. 6 in., and those under the 
west wall 4 ft. 6 in. by 3 ft. The corner piers were made square to the larger 
dimension in all cases. The trench concrete is reinforced with steel girders, 
and these act as beams for supporting the walls. 

The reinforced concrete columns are square, with chamfered angles, mea- 
suring 16 in. bv 16 in. on ground floor and 14 in., 12 in., 10 in. and 9 in. 
respectively on first, second, third, and fourth floor. They are reinforced with 
rib bars, there being eight |-in. rib bars in the ground and first floor columns, 
four i-in. rib bars in those on second floor, four |-in. at third floor level, and 
four i-in. supporting roof. All are bound with re-in. wire at 12-in. centres, and in 
the case of those at ground and first floor levels are cross bound in addition. 
Spanning these columns a continuous beam reinforced with Kahn and rib bars 
(the latter bent over supports for continuity) and 2^ in. deep by 9 in. wide runs 
the full length of the building, and this, apart from the staircase and lintels, is 
the only beam on each floor, the span to walls on either side being flat on soffit, 
constructed in the Kahn tile system. These hollow tiles are uniformly 
12 in. by 12 in. on plan, and vary in height according to the depth of floor as 
called for bv the requirements of load and span. They are placed in rows across 
the span, a 4-in. interval separating each row, the tiles being stopped some 
distance from the beam, so that the table of the beam may be formed in solid 
concrete for T action. The concrete is then cast in the troughs between the 
rows of tiles (embedding the reinforcement) and is floated over the tiles to the 
required depth, thus constituting a monolithic series of small continuous T 
beams. The tiles in this system are not called on to do work, but merely to 
occupy space and give a flat soffit. These spans are, as mentioned above, 
14 ft. 6 in. and 22 ft., but it is interesting to know that spans of 30 ft. to 40 ft. 
are possible in this method. In the cSse of the 22-ft. span, the 12 in. depth of 
floor is made up with to in. tiling and 2 in. of concrete, while for the root 8 in. 
depth of tiling with 1 in. concrete float sufficed, the reinforcement consisting 
of §-in. bars on [6-in. centres, thus giving the concrete joist between tiles a 
width of -| in. 

The staircase is carried by 14-in. cranked stringer beams 6 in. wide, rein- 
forced with rib bars in the bottom. 

All the walls, columns and ceilings in the main building are plastered with 
Si raphe 

The concrete was composed of > part by volume of Portland cement, _| 
parts of washed river ballast crushed to pass a |-in. mesh, and 2 parts ol sand. 

90 



f y „ C'ONM L-ulTlONA I ] 
[f\ ENGINEERING — J 



REINFORCED CONCRETE RUBBER WORKSHOP. 



NEW TELEPHONE WORKSHOP. 

This is a building of six floors with n mean length of 325 ft., width of 45 ft., 
heighl from basement floor to underside of roof 7S ft. There is a large 







F. SOU THEY 



[OaNGKETEl 




f /, CON.VI 'IHKTIONAl.l 
1A E NGINEERING — J 



REINFORCED CONCRETE RUBBER WORKSHOP. 







F. SOUTH EY. 



.CONCRETE 



machine shop of one storey adjoining this building on the north side with a 
saw-tooth roof and n floor area of 38,300 sq. ft. 





This building presents many constructional features similar to that of the 
new rubber workshop, so thai a briei reference to the leading points of difference 
would suffice. 

9 + 



[AgESESSB^ g REINFORCED CONCRETE RUBBER WORKSHOP. 

The foundation piers are placed at iS-ft. 6-in, centres, and a scries of 
continuous reinforced concrete foundation beams afford dired support to the 
brick wall piers, which arc spaced 9 ft. 3 in. between centres. The columns 
under ground, first and second floors arc all wound with helicoidal rein! 
ment. This was supplied to required diameter ready coiled, and was fixed and 
wired in place according" to pilch. 

A single continuous longitudinal beam on every floor and roof extends the 
whole length from column to column, intersected by secondary transverse beams, 
each of which has a bearing at one end on the wall pier. 

A parapet wall with a concrete coping serves both as a suitable finish, to the 
south side fronting the street and a means of affixing the title of the firm in 
skeleton letters. 

It may here be stated, in conclusion, that Mr. \V. Dfeselhorst, the works 
general manager of Messrs. Siemens Bros. & Co., was responsible for the general 
design of the whole scheme, the architects being Messrs. Herbert and Helland, 
on the staff of the same firm. Messrs. Holland & Hannen were contractors for the 
two large builings, and Messrs. Mowlem & Co. the contractors for the smaller 
building — viz., the new offices and store. The Trussed Concrete Steel Co. were 
the specialists for the reinforced concrete work, and supplied all the steel 
reinforcement. 



95 



E. J. STEAD. 



TONCBEXEJ 






~ 




1 



STOPPING PLANES IN 
REINFORCED 
CONCRETE. 



By EDWARD J. STEAD, Assoc.M Inst.C.E. 

The question of Stopping Planes in reinforced concrete is one that still calls for much 
attention and study, and the following article on the subject may therefore prove of interest 
to our readers. - ED. 

It appears to the writer from considerable experience of reinforced concrete 
construction that insufficient consideration is as a rule given to the determination 
of positions of stopping- planes in this class of work. 

Beams and Slabs. — In concreting beam and slab works it is a common 
practice to fill up the beam forms to the level of the underside of the slab, then 
at a later stage of the work to follow over with the slab concreting separately. 
During the interval the surface of exposed concrete receives more or less injury 
from dirt, etc., and it has frequently been noticed that the shear reinforcement 
gets flattened down and knocked out of shape. These circumstances result in 
a plane of weakness as regards horizontal shearing on the line a — b in Fig. i. 
It has further been observed that the stopping planes in the slab concreting are 
often made vertically over the longitudinal centre lines of beams, as at c — d in 
Fig. i. 

In this type of design the beams are in general calculated as T-beams, and, 
notwithstanding the fact that many successful constructions have been carried 
out in the method indicated, it is submitted that it is undesirable to make 
temporary joints in the positions shown. Xo matter how carefully the surfaces 
are cleaned and roughened the homogeneity so greatly desired cannot be 
secured. 

To obtain the full value of the area of concrete in compression — i.e., that 
portion of the beam proper which lies above the neutral axis, together with 
the width of the slab acting with it — stopping planes should be excluded so far 
as practicable from that area. Unless the vertical reinforcements in the beams 
maintain their intended shapes and positions, are rigidly attached to the tensile 
reinforcement, and well concreted into the compression area, the resulting 
construction approaches that of a rectangular beam of depth a — e with the 
slab resting upon it, and the strength will be considerably less than the 
designer intended. 

As a matter of practical construction, stopping planes must occur some- 
where in the concrete, and it is suggested that in the case of beams in one- 
direction only — i.e., no secondary beams — the better practice is to cast the beam 
and slab in one operation, as shown in Fig. 2, in which the dotted lines / — g 
and h—j represent joint lines parallel with the beams and at the centres of the 
slabs between them. There can be no serious objection to the joint thre)Ugh 

96 



tegasagga^gj stopping planes in reinforced concrete. 

,1k ' slab ' ;,s [1 is ;,t ri & hl angles to the direction of the main reinforcement the 
bars of winch being continuous over two or more beams ensure full tensile 



d 7> 

7 — 






r/o. / 




JJCrl fn 



h 



7 



Jfert. 77Z. 



r/o.2 



JSecLTrr 



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-i 



strength being- available. 



rfijjfc-!? 



',51 -<b 



rei+ttorcefr\ 



tSe < \ 7nr7aj 



i' J?e, 



//G.J 



A temporary face board would be necessary to keep 
a vertical face of concrete to join up against on resuming. The upper part of 



97 



E. j. stead. [ C3NCREXE1 

the slab being- in compression the action under loading will be simply pressure 
on the two concrete faces, and the shearing stress at the joint will be nil. 

In constructing larger floors where there are both main and secondary 
beams a somewhat similar method is desirable. For the purpose of illustration 
a floor has been assumed as in Fig. 3, where the main beams, supported at 
intervals by columns, run the short way of the building, and between the main 
beams are the secondary beams with a slab over all. 

Here the main beams and column connections demand special notice, and 
from theoretical considerations the concreling would be most advantageously 
carried out in bays across the short way of the building, each bay comprising a 
main beam and portions of the attached secondary beams and slabs, the joint 
lines being along the centre lines of slabs and parallel to the main beams, as 
shown by the broken lines a — a. Complete homogeneity would thus be 
assured to the main beams and the portions of the slab acting therewith as a 
T-beam, there would be no break in the work over or around the column heads, 
and so far as the secondary beams are concerned the stopping planes would be 
in the most suitable positions — viz., at the centre of the span and at right angles 
to the direction of the beam. 

Assuming, however, that the size of the building is such thai the volume of 
concrete in one bay, as indicated, is too great to be put in without a break, it 
will be necessary in order to reduce the amount of work to be done in one 
operation to make stopping planes through the main beams. The first point 
then calling for notice is the necessity for avoiding a break at the points of 

span 

inflexion (which are at approximately from the supports) on account of 

4 
the shearing action at such points. A stopping plane could most advantageously 
be made at the centre of middle span — i.e., in the line b — b. 

In no case should concreting be stopped in beams or slabs where shearing 
stress is likely to be great, as at a point near the supports or under a heavy 
concentrated load. 

It is necessary to fix the whole of the reinforcement in beams before 
concreting is commenced, but in the case of slabs a common practice is to lay 
the bars down a few at a time as the concreting proceeds. The adoption of the 
stopping planes advocated above necessitates the fixing of the slab bars in 
advance of the concreting — a decided gain as regards accuracy of spacing and 
the ultimate strength of the work. 

Columns. — In general, stopping planes in columns present no difficulty, as 
they are usually concreted for the full height between floors at one operation. 
Even if this does not occur, provided the concrete is temporarily left with a 
horizontal surface, and kept clean and free from foreign matter, no weakness is 
incurred, as the joint will be at right angles to the pressure upon it. 

Arches. — The stopping planes in concreting arches may occur, according 
to the magnitude of the arch, either longitudinally or transversely. In each 
1 ase both the upper and lower reinforcements should be placed and fixed 
securely in position prior to commencing concreting. Where possible a strip 
the full thickness of the arch should be concreted from abutment to abutment in 
one operation, the temporary joint being made against a profile erected on the 

98 



lAgSoSSiff^ STOPPING PLANES IN REINFORCED CONCRETE. 



laggings in the case of longitudinal reinforcement only, or In the case of mesh 
reinforcement by short boards set vertically between the meshes, as shown in 
Fig. 4 

In concreting sections of the arch transversely the stopping planes should 

/Se cUo // Co be ci/wrr* />■</ 

Vr//r/f<?/-a/-y at one o/aeraCion- 

/ace \\ 



i /(7cc board 



rt 




f. fX <?<? I ' Zi '_ r? 



Fig 4. 

Stopping Planes in Reinforced Concrete. 



be at right angles to the line of pressure, or, for all practical purposes, 
perpendicular to the curve of the arch at the point, and, where possible, it is 
preferable to concrete a section the full width of the bridge at one operation. 

The temporary joint in this case will be 



■0^4 



made against a straight shutter of such 
depth as to be a very easy fit between 
the upper and lower reinforcement, 
such shutter being slipped in from the 
ends and temporarily secured at the 
proper angle. On recommencing, the 
shutter will be drawn out, the face 
boards fixed, and concreting proceeded 
with. The formation of a stopping- 
plane of this description is shown in 

Fig- 5- 

By careful consideration beforehand 

the positions of stopping planes ought 
to be determined and then worked to. Too much emphasis cannot be laid upon 
the necessity for thoroughly cleaning, roughening, and laying thick grout upon 
all stopping plane surfaces when concreting is recommenced. 




Fi4. 5. 
Stopping Planes in Reinforced Concrete. 



Q9 



REINFORCED CONCRETE WHARF AND JETTY. 



[CONCRETE] 

1 




reinforced concrete 

wharf and jetty 

at saint-louis, 

s£n£gal. 



The foltoiving interesting article has been compiled for us by Mr. G. C. Workman, and 
is based on an article -which appeared in the French Journal, ' ' Genie Civil, " by Mr, Alfred 
Jacobson, Civil Engineer (France). — ED. 



The important works described in this article, which have recently been completed, 
are of special interest on account of the fact that they were executed entirely by native 
African labour, under the supervision of a few French engineers. 

The work comprises an extensive wharf on one side of the river Senegal, and a 
quay or wharf continued as a jettv on the other side of the same river. The total 
length of these wharves, quays and jetties, altogether about 1,200 m., was entirely 
constructed in reinforced concrete on the Coignet System. The work was put in 
competition in December, 1910, among French contractors specialising in reinforced 
concrete. After careful consideration of the various schemes put forward, Mr. Merlaud- 
Ponty, Governor-General of the French West Coast of Africa, decided to entrust the 
execution of the work to Mr. Edmond Coignet, of Pari-. 

The contracts concerning the construction of the wharf and of the quay and jetty 
were respectivelv signed on April 22nd and December 1st, 191 1. 

As this work was to be executed by natives and in a distant country, Mr. Coignet 
thought it advisable to carry out the work in collaboration with Mr. G. Touzet, con- 
tractor at Dakar, the latter being already thoroughly acquainted with local conditions. 

The wharf, which has been constructed for the accommodation of steamers, 
measures 242 m. in length, and has a total surface of about 3,000 sq. m. ; 2,500 sq. m. 
of this total surface is constituted by a deck in reiniorced concrete, and the remaining 
500 sq. m. is constituted by a filling of earth at the back of a certain portion of the 
wharf. The work has been calculated to support a superload of 2,000 kilogs. per sq. m. 
The total length of the wharf is divided up into two different sections : — 

1st. An upstream section of no m. in length, with a width of 13 m., in which the 
deck is supported on three rows of piles and upon a wall in masonry work already 
existing. 

2nd. A downstream portion of 132 m. in length and 8*40 m. in width, in which the 
deck is supported by three longitudinal row- of piles. In this case the extra width of 
the wharf is made up by an embankment of earth retained by means of sheet piles, as 
shown in Figs. 2 and 3, 

The reinforced concrete piles, of which there an' 147, an- spared longitudinally 
every 5 m. and transversely every 4'ii m. centres in the upstream portion, and every 
4 m. in the downstream portion of the wharf. The piles of the middle row have a 
diameter of 0*38 m. and those in the two lateral rows have a diameter of 0*33 m. These 
piles were driven down to a hard stratum situated at a depth varying between — 12*50 m. 
and 14 m., the top of the deck being at a level of + ['80 m. The height of the various 
points of support therefore varies between 14 m. and i<> m. 

The reinforced concrete deck is composed of n slab o*io m. in thickness, supported 
100 



I 



CON.STRI JCTIONA L) 
ENGIMfcERlNG- 



5aO 
! — I 



REINFORCED CONCRETE WHARF AND JETTY. 



by longitudinal beams having a span of 5 m, and scantlings of o'i6xo*3o, the Latter 
being supported by the piles, or by principal beams having scantlings of o'33xo*45. 
Gussets were provided in order to contribute to the rigidity of the work. 

Fig, 5 shows a detail of the reinforcement of the deck and of the arrangement of 
the beams. The reinforced concrete slab of the deck was covered by means oi a 
pavement made by placing by hand pieces of very hard stone into a layer of rich concrete 
to a thickness of o' 10 m. 

The reinforced concrete sheet piles acting as a retaining wall had a section of 
0*12 x 0*33. They were fitted with tongue and groove. The sheet piles were driven 
i 111. into the ground and fixed at their top into a longitudinal beam. As an extra 







mmv 8 ^' 



& 



~)Cimetu 



Fig. 1. Plan of th? Town of Saint Louis. 
Reinforced Concrete Wharf and Jetty, Saint-Louis, Senegal. 



measure of precaution, every 5 m. in front of the principal beams land ties have been 
provided. These are covered in concrete and anchored at one end into the reinforced 
concrete deck and at the other into vertical reinforced concrete plates 1*25 m. by 
1-25 m. 

By looking at section No. 5 it will he seen that an apron o'io 111. in thickness has 
been provided in front of tin- work, and between the front longitudinal piles. Thi 
to prevent the small boats from going underneath the platform. 

The jetty and wharf on the other side of the river near the railway s 
composed of an approach of 140 m. in length and 5*65 in. in width, joined 
end, which is designed for ships to come alongside, and which measures 

ICI 



REINFORCED CONCRETE WHARF AND JETTY. [ CONCRETE 







J i \ 



I02 



f&E^&Tffffi j REINFORCED CONCRETE WHARF AND JETTY. 

length and [0*33 m. in width. Sec Figs. 7 and 8. The total ana of the wharf 
measures i ,300 sq. m. 

The work has been calculated for a uniformly distributed load of 5,000 kgs. per 
sq. ill. 




Ihe 147 piles included in this work have been arranged at distances of 4 m. 
There are only two rows of piles in the approach and three or four in the widi r part at 
each end of the jetty. These piles have a diameter of 0*33 m., except those in (he r 
portion where there are more than two rows of piles, where their diamel is 040 m. 
The slab of the deck is o"io m. in thickness, with way beams of o - 22 x 0*40 and secondary 



REINFORCED CONCRETE WHARF AND JETTY. [CONCRETE] 




104 



[jlllllgigg REINFORCED CONCRETE WHARF AND JETTY. 

beams of o*i6xo"25. The transverse beams measure o*33Xo - so and the braces uniting 

the various piles measure o'2oxo*30. 

All the steel bars and the cement used in this work were sent from France, 
sand and gravel, however, were used for the aggregate. The concrete was mixed b\ 
means of salt water taken from the river. 

The execution id" the work was divided into three parts : — 

Firstly, the moulding of the piles, sheet piles, and anchor plates, and also the 
preparation of the braces for the jetty ; secondly, the driving of the piles and sheet piles ; 
and thirdly the making in situ of the deck. 

The first portion of the work mentioned above, comprising the moulding of piles, 
etc., is illustrated in Figs. 6 and 9, where natives are seen preparing the reinforcement 
of the piles and ramming the concrete into the moulds. The piles were left to mature 




Fig. 6. View of Site for making Piles, and Natives making Framework for a Pile. 
Reinforced Concrete Wharf and Jetty, Saint-Louis, Senegal. 

on the ground in the usual manner and steel moulds were used. It was usually possible 
to remove these at the end of 24 hours. After about a month the piles were leaded on 
a 50-ton steel barge, and they were taken on to the site of either the wharf or the jetty 
to be driven. 

1 he work of driving the piles was carried out by means of a steam pile driver of 
the Decout-Lacour type. The position of the monkey was cantilevered at a distance of 
5-60 m. from the wheels supporting the pile-driver, this weight being counterbalanced 
by the boiler at the other end of the structure. The total weight at the cantile 
extremity was 2 tons for the monkey and 5 tons for the pile during the pitching 
latter, giving a total of 7 tons to be counterbalanced by the weight of the boil 
other counterweight required. 

The peculiar arrangement of this pile-driving apparatus was n 
tact that the reinforced concrete piles already driven were being made use o drive 

105 



REINFORCED CONCRETE WHARF AND JETTY. 



[C ONCRETE! 



the uncs in front. The pile-driving apparatus was capable of rotating upon an axis, 
and also of a longitudinal movemenl along rails, so that it was possible to pick up 
the piles from a barge lying alongside, to hoist them in the air, and pitch the pile in 
the required position for driving. The total height of the driving apparatus was 
15 m. The t< tal weight id the apparatus was 22 tons. As soon as a row of piles was 
driven the heads of these were connected together by mean- of wooden bracings, and 
a temporary platform was constructed upon which the pile-driving plant was shifted, 
in order to bring it into position for the driving of the next row. 

A noticeable feature was that as soon as the braces were connected on to the new- 
row of piles, the pile-driver was shifted in such a way a- to bring its entire weight on 
two rows of piles. The apparatus would then pick up the beams of the deck at the 
back, and, turning round again, these beams would be placed on the top of the 
new piles which had just been driven. The platform or deck was then completed, and 






_ 70TS3 

(+ , i,.qo v 



1 




Figs. 7 &. S, Transverse Section, left bank of river. 
Reinforced Concrete Wharf and Jetty,. Saint-Louis, Senegal. 



il was then easy to roll the bogeys into position at the centre of each bay, in order to 
distribute the weight of the pile-driving apparatus once more upon three rows of piles. 

The advantage of this method of proceeding was found in the economy over a 
temporary staging, which would otherwise have been required, and the difficulties 
which there would have been in fixing such a staging in a sufficiently rigid manner to 
enable the handling and driving of these heavy piles in reinforced concrete without 
any danger. 

Concerning the actual pitching and driving of the piles, this was carried out in the 
usual manner, the pile being lifted by the head. 

When the piles were lifted at the head, the end resting on the ground, there was 
a total deflection in the middle equivalent to approximately the diameter of the pile — 
namely, for a pile of i4 - 2o-m. length a deflection of as much as 0*33 m. was noticed. 
In each case, however, the pile regained its original straightness without showing any 
injuries, which is an example of the gnat flexibility of reinforced concrete. 

The piles of o"3S-m. diameter of the middle row were driven with a 2-ton monkey 

106 



Tg r CONSTEUCTIONAIJ 

LA eisgtneLring^-J 



REINFORCED CONCRETE WHARF AND JETTY. 



until they had reached a set of o*oi for twenty blows of the monkey falling from a 
height of < > • j 5 m. The piles of 0^33 diameter of the lateral rows were driven to a sel 
of o'oj for twenty blows of the monkey falling from a heigbl of 0*25. This sel corre- 
sponds to the loads which the piles were calculated to support namely, 60 tons for the 
piles 0*38 diameter and 32 tons for the piles 0*33 diameter. 

Once the piles were driven the work of making the beams was proceeded with. 
The slab, however, was not constructed immediately after the beams, which is the 
usual practice, but about a fortnight later. In this manner it was possible to utilise 




Fig. 9. Natives Concreting a Pile. 
Reinforced Concrete Whirf and Jetty, Saint-Louis, Senegal. 

the cheeks of the beams to support the centering of the slabs and the weight of the 
latter during the concreting. This method of procedure enabled the contractor- to use 
comparatively light scantlings for the woodwork of the centering. 

As shown in Fig. 10 the transverse braces for the head- of the piles, which 
already been placed in position for the proper supporting of the pile-driving 
were left in position and actually formed the centering for the transverse 
that the fixing together of the heads of each row of three piles served not 



107 



REINFORCED CONCRETE WHARF AND JETTY 



[CONCRETE 



purpose of steadying the piles to support th< pile-driver, but also a- a centering and 
staging for making cross-beams and supporting the deck during the construction. 

Concerning the reinforcement of the beams and slabs, this is clearly shown in 
Fig. 5, where it will be seen that the beam- are composed of a ^roup of round bars. 
These bars have their ends gradually bent up at an angle of 45 and hooked to a longi- 
tudinal top bar, the advantage of this method being that the end- of the bars, which are 
no longer required to counteract the gradually decreasing bending moment, are made 
L ise of to counteract the gradually increasing -hear towards the points of support. 




Pig. 10. General View of Wharf, right bank of river, during execution. 
Reinforced Concrete Wharf and Jetty, Saint-Louis, Senegal. 



The frameworks or units of these beam- were prepared beforehand by the natives 
and brought into position and simply hung into the casings. The system here adopted 
has been found specially suitable when- native and unskilled labour has to be employed, 
because it ha- the advantages that once the unit reinforcement is prepared separately 
and beforehand, all thai i- necessary i- to suspend it in the moulds during the concret- 
ing operation, and all the bars being hound together tightly, they cannot easily get 
out of position during the ramming of the concrete. 

The framework of the slabs of the deck was simply composed of a meshwork of 
principal and se< ondarj !>ars. 

;o8 



fo„ CONSTRUCTIONAL 
IA ENGINEERING — , 



REINFORCED CONCRETE WHARF AND JETTY. 



Concerning the jetty and the wharf alongside of same, these were constructed in 
a somewhat different manner from the principal wharf already described. Tin jetty 
was constructed by first driving the piles in the usual manner and by fixing the 
walings constructed beforehand in the manner shown in Figs. 11 and 12. This arrange- 
ment consisted in chipping off the concrete at the required level around the piles, and 
fixing the bars of the walings around the chipped portion in the manner shown in the 

up. In this manner it was possible to drive the 
piles to their full height 
without having to make 
the walings and uprights 
in silu. The variations of 
temperature during the 
day were between 30 and 
-m° Centigrade in the sun. 
During the periods of wind 
coming from the desert the 
temperature, however, was 
much higher. It was 
necessary, of course, to 
protect the work against 
this considerable heat, and 
for this purpose the con- 
crete was covered over with 
a layer of sand of 1 or 
2 cm., almost immediately 
after the concrete was 
placed in position. This 
sand was kept continually 
in a moist state until the 
concrete was at leasl 
twenty days old. This 
simple precaution w a s 
found to be quite sufficient 
to protect the work from 
the heat of the sun. 

Concerning the labour, 
the men employed on the 
reinforced concrete work, 
either for the preparation 
of the steel frameworks, 
the centering, the concret- 
ing or the handling and 
driving of the piles, were 
all natives, very few of 
whom had anv other trade 
but the loading and unloading of barges on the river. The method employed for 
carrying out the work was to form a certain number of gangs, the members of which 
were recruited by a few of the more intelligent natives, some of Whom had a knov 
of carpentry, or who were already accustomed to direct the men in the loading ; 
unloading of the barges. It was found that under the direction of these chi 
the work proceeded in a satisfactory manner, and, although in certain 1 . 
labourers had only recently come from the interior of the country and were no! 

109 




REINFORCED CONCRETE WHARF AND JETTY. [CONCRETE 



turned to any special kind of work, they very soon understood what was required, and 
were able to carry out their work as effectively as the others. 




Fig. 13. Preparation of Centering for Deck of Wharf, right bank. 
Reinforced Concrete Wharf and Jetty, Saint-Louis, Senegal. 







*> 



Fig. 14. Wharf Partly Completed, right bank of river. 
Reinforced Concrete Wharf and Jetty, Saint-Louis, Senegal. 




r y. CONSTWICTIONALI 



REINFORCED CONCRETE WHARF AND JETTY 



Concerning the progress of the work, the 1.(7 piles of the main wharf were 
between November 25th, dm, and March 25th, 1912 namely, in four months. The 

area of 2, 500 sq. m. of deck was executed between February ioih, 1912, and April 25th, 
[912 namely, in two and a half months. Seeing thai the manufacture of the piles 
was begun before November, 1911, and thai the execution of the final pavement on the 

deck was finished after April, 1912, it may be stated in conclusion that the main work 

of this wharf was carried out between November 25th, 1911, and April 25th, 1912 

namely, five months, which, taking into account the difficult nature of this ki 
work in any case, the local conditions and the native lahour, shows that reinforced 
concrete is eminently suitable for structures of this kind in the colonies. 

The work of the various wharves and jetties was executed under the control of 
the Administration of Public Works in Senegal, represented by Mr. Guyot, Chief 
Engineer, and Mesrs. Michas and Roily, Assistant Engineers, and .Mr. Roum6goux 
Inspector. 




Fit;. 15. Concretirm on Deck of Wharf, left bank cf river. 
Rkini-orced Concrete Wharf and Jetty, Saint-Louis, Senegai 



JAMES L. DAVIS. 



[CONCRETE! 




IMPERMEABILITY TESTS 
ON CONCRETE. 



By JAMES L. DAVIS. 



Section Engineer, Board of Water Supply, New York City. 

The folloiving tests tvere maae by the author tohen he -was in charge of the Laboratory 
of the New York City Board of Water Supply, in connection -with the design of the Catskiil 
Aqueduct. The results "were later incorporated in a thesis submitted to the University of 
Vermont and the present abstract takes up in order the effect upon the permeability of 
concrete of the inclusion of hydrated lime, puzzolana, clay, very fine cement and additional 
cement, and in addition gives some neiv figures on the variation ivith the pressure of leakage 
through concrete. This article is reprinted from the American Journa', "Engineering 
News. ' ' - ED. 



The use of hydrated lime as a means of rendering concrete structures impervious to 
water has received the attention of several investigators, whose experiments have 
generally shown favourable results from its use. Engineers have employed this material 
in waterproofing reservoirs and tanks and have secured watertight structures. 

The tests described below were undertaken with a view to determining the merits 
of this material and also puzzolan cement made by grinding together a mixture of blast- 
furnace slag and lime. Two brands of hydrated lime were used, a high calcium and a 
magnesian lime, each being a high-grade representative of its class. A single brand of 
puzzolan cement was used. 

The tests were based for ready comparison on plain concrete in proportions 1:3:6 
bv weight. A lean mix was adopted to insure measurable leakage of the blanks. The 
increasing prcportions of cementing materials used are given in the tables as fractions 
of tlie basal proportions of cement in order to show in an elementary manner the scheme 
adopted. The aggregates used were ordinary quartz sand and gravel supplied from 
Long Island banks for the New York market. The sand all passed a sieve with o - 2-in. 
square openings. The gravel passed the 1*75 in. and was retained on the 0'2-in. sieve. 
The densitv as well as the strength and permeability of the various mixtures was 
investigated. 

The densitv test is becoming one of the recognised means of determining the 
properties of mortar and concrete. The density of concrete is defined as the ratio of the 
sum of the volumes of the solid particles, cement, sand and stone in the mix to the total 
volume of set concrete. It is the complement of the air and water voids. The methods 
of determining density will not be given here. (See " The Laws of Proportioning 
Concrete," bv William B. Puller and Sanford E. Thompson, Transactions Am.Soc.C.E., 
Vol. LIX.) 

The permcabilitv test specimens were cylindrical, 8 in. in diameter and 6 in. in 
length. About two weeks before testing the specimens were chipped with chisel and 
hammer to remove the " skin " and were enclosed over the sides and one end by neat 
cement casings poured around and over the specimens which were centered in circular 
moulds 12 in. in diameter. A pipe connection extended through the casing in line with 
tin- axis of the cylinder and terminated in a cushion of coarse, washed sand 1 in. in 
thickness, covering the end of the specimen. This sand cushion prevented the mat 
cement paste with which the casing-, were made from coating the end of the specimen 
and permitted the water to act over the full end area. The specimens being coupled to 
vertical outlets from the bottom of a pressure tank, the water was forced to traverse 
the entire thickness of the concrete and was caught and weighed as it dripped from the 
exoosed ends. The leakage recorded is the total weight passing during the last ro-min. 
period of the i-hr. lest. Previous studies have shown that fairly uniform conditions 



I I 2 



[&e^nejIj»ng^ impermeability tests on concrete. 

of flow arc established within the hour when (jesting under the pressures used, 40 and 
80 lb. per sq. in. The strength specimens were cylindrical, (> in. in diameter and 12 in. 
in length. The bests were made on a too,ooo-lb. screw-power testing machine, the 
crushing tool being fitted with a spherical bearing. The specimens were cushioned top 
and bottom with two thicknesses of blotting-paper. 

In the tabulated results several minor inconsistencies appear; To maintain com- 
parable conditions throughout a series of concrete tests is a difficult matter. Both 
permeability and strength tests are greatly affected by slight excesses or deficiencies in 
the amount of mixing water used. The required amount of water varies with the brand 
of cement and its degree of fineness, the fineness of the aggregate and other factors. 
Final determination of the proportion of water depends in some measure on the judg- 
ment of the operator. Under 40-lb. per sq. in. water-pressure Portland cement com p i< 
in proportions 1-2:3:6, or richer, and all proportions of hydrated lime used give 
impervious concrete. Puzzolan cement in proportions 1*3 : 3 : 6, or richer, gives nearly 
impervious concrete. 

At 80-lb. pressure several of the above described mixes are practically impervious, 
and none of them give much leakage. 

High calcium lime is the only material giving entirely consistent results in dec Teas- 
ing permeability in proportion to the amount used. It is possible the richest proportions 
of magnesian lime and puzzolan cement were too dry for best results. (See tabulated 
percentages of water in Table I.) Averaging all comparable proportions the relative 
strengths at 3 mo. age are as follows : 

Port'and cement. Calcium lime. Magnesian 'ime. Puzzo'an cement. 

100 per cent. 85 per cent. 76 per cent. 81 per cent. 

The density tests show unexpectedly uniform results throughout the series. 
Hydrated lime alone yields about 2\ times the volume of paste thait an equal weight of 
Portland cement does. A record of the volumes of rammed concrete produced in the 
tests was kept as a check on the volume computed from the density tests. 

Comparison of volumes as tabulated is based on the volume of the plain concrete as 
■a unit. The lime does not have an appreciable effect in increasing the volume of 
concrete ; neither does it increase the density. The result is an apparent paradox. 
Tests on the richest cement-lime paste used in comparison with cement paste showed the 
cement-lime mixture gave an increase in volume of paste of 29 per cent, over plain 
cement paste. The density of this paste was 0*42. It was, therefore, very porous and 
must have contained a large amount of free water. The density of the plain cement 
paste was 0*52. 

Comparison of the relative volumes of solid particles in the two pastes resulting 
from equal weights of dry materials is made as follows : 

Volume of cement-lime paste equals 129 per cent, of cement paste. 

1 '00 x 0*52 = 0*52 = relative total volume of solid particles in cement paste. 

1*29 x 0-42 = o'54 = relative total volume of solid particles in cement-lime paste. 

The reason for the failure of the lime to produce measurably denser concrete thus 
becomes evident. The low density resulting offsets the increased volume over cement 
paste. Comparison of the density computations, not here given, showed that a smaller 
volume of air was entrained in the concrete where lime was used. The failure of the 
lime to give an increased total volume of concrete was due to the replacement of free 
water and entrained air in the plain concrete by the porous, water-filled, cement-lime 
paste. This paste simply occupied space which in the plain concrete was filled with 
water and air, and therefore no appreciable increase in gross volume resulted. 

This latter result suggests that the use of this mixture of cement and lime should 
cjive superior water-resisting concrete by filling the larger interstices between the 
particles of aggregate with this paste. While this paste will not reduce the total 
percentage of voids in the mass, it will fill the comparatively large-si/ed pores — through 
which water can pass quite readily — with this fine-pored substance, thus offering much 
resistance to flow. 

The permeability tests here given hear out this deduction to some extent, particularly 
in the tests at 40 lb. pressure. The practical advantage does not, however, appear from 
these tests to be sufficient to merit much consideration. 

With cement-lime paste, the maximum density any paste-filled cavity can have 
0*42 ; with cement paste it may be 0-52. 
n 



JAMES L. DAVIS. 



[CONCRETE) 



Tests by other experimenters, as well as other tests by the writer, have shown the 
density of cement paste to average about 6'6b for pastes of ordinary consistency. Using 
this value, the merits of this cement-lime paste compare less favourably than above. 

Based on prices in New York markets, plain Portland cement concrete costs 
slightly less per cubic vard for materials than any of the other mixes containing equal 
proportions of cementing materials. For equal efficiency in waterproofing at 40 lb. 
pressure the use of hvdrated lime reduced the cost of materials about 5c. per cubic yard 
of concrete. 

Puzzolan cement was at a disadvantage in this comparison on account of the 
remoteness of the mill from New York and the consequent high freight charge. 

Conclusions.— (i) Hvdrated lime is effective in producing impervious concrete, but 
its use is doubtful economy, except, possibly, for resisting low pressure of water. 
Concrete in proportions 1:3:6 requires the addition of a proportion of lime equal to 
about 20 per cent, of the weight of the cement for efficiency against high pressure. 
This results in a slight loss in the compressive strength of the concrete as compared 
with the plain 1:3:6 mixture. 

(2) It is probable it is not an economical material for structures subjected to tensile 
stress, such as reinforced conduits. 

(3) Except possibly for low pressures, equally good results in impermeability can 
be obtained bv the same cost invested in additional cement, with resulting stronger 
concrete. 

(4) The addition of lime increases the plasticity and mould-filling properties of 
concrete, resulting in smoother surfaces against forms. Its use may give practical 
advantages in filling around reinforcing steel and in other restricted spaces. 

T\BLE I. Permeability and Strength Tests of Concrete, Effect of Hvdrated Lime and PuzroLAN Cement 









Leakage 




















in grams. 


Compara- 


Lb. 


Compara- 




Water, 


Cost of 


Cement. 


Proportions 






tive 


per 


tive 


Density. 


per 


material 






veight. 


Pres- 


Pres- 


strength, 


sq. in., 


vie d. 




cent. 


per 








sure, 


sure, 


28 days. 


3 months. 


volume. 






cu. yd. 








40 lb. 


80 lb. 














Group A : Portland 


1 


: 3 : 6 


6 


47 


745 


1.535 


i-ooo 


0-857 


7-8 


S 

3-5I3 




r-r 


: 3 : 6 


33 


77 


650 


1,180 


1-035 


0-812 


8-4 


3-512 




1-2 


: 3 : 6 





2 


920 


1,860 


1-045 


0-788 


8-3 


3-608 




i'3 


: 3 = 6 








910 


2,000 


1-069 


0-805 


8-5 


3-633 




1-4 


: 3 : 6 





18 


1,070 


1.95° 


1-069 


0-790 


8-7 


3-769 


Group B : Portland 


I-I 


: 3 : 6 





20 


800 


1,615 


1-032 


0-816 


8-o 


3-563 


and high calcium 


1-2 


: 3 : 6 





12 


680 


1,320 


1-038 


0-804 


8-7 


3-679 


lime 


1-3 


: 3 : 6 








595 


1,33° 


1-069 


0-793 


9'3 


3-704 


Group C : Portland 


i-i 


: 3 :6 





4 


475 


830 


1-038 


0-789 


9-1 


3*553 • 


and magnesian 


1-2 


: 3 : 6 


n 





765 


1,460 


1-069 


0-793 


8-8 


3-6i7 


lime 


1-3 


: 3 :6 





14 


760 


1,545 


1-069 


0-789 


8-8 


3-794 


Group D : Puzzolan 


I 


: 3 : 6 


5 


22 


600 


880 


1-006 


0-822 


7-6 


3-642 


only 


I-I 


: 3 : 6 


13 


25 


490 


i,4L5 


1-017 


0-833 


8-o 


3-747 




1-2 


: 3 : 6 


7 


45 


580 


1,345 


1-030 


0-798 


7-8 


3-841 




i - 3 


: 3 : 6 








620 


1,305 


1-028 


0-784 


7-9 


3-974 




1-4 


: 3 : 6 





6 


910 


^OS 


1-075 


0-817 


7-7 


3*949 



The fractional parts in cement column of Group A are excess Portland cement ; in Group B, calcium lime ; in Group C , 
magnesian lime ; and in Group D, excess puzzo'an cement. 

Permeability specimens, cylinders 8-in. diameter, 6 in. in length. Tested at 40 lb. pressure per sq. in. for one hour, 
then at 80 lb. one hour without interruption. Three specimens in each average. 

Portland cement : tensile strength, 1 : 3 Ottawa sand, 28 days, 306 lb. per sq. in., sp. gr. 3-16, Thru No. 200-mesh 
sieve, 80-5 per cent. . 

Puzzolan cement ; tensile strength, 1 : 3 quartz sand, 28 days, 146 lb. per sq. in., sp. gr. 2-90, Thru No. 200-mesh 
sieve, 95-8 per cent. 

Compressive specimens, cylinders 6-in. diameter, 12 in. in length, 28 day tests on one specimen usua'ly. 

I bree months tests the average of three specimens in all cases. Permeabi ity tests made at 28 days ag< . 

( fuoted prices in New York, per ton : Sand, Si. 08 ; gravel, Si. 40 ; Portland cement, S6.7S ; Puzzolan cement, S7.60 
high eal( nun hydrated lime, S8.00 ; magnesian hvdrated lime, S9.50. 

(:;) Puzzolan cement is slightly less efficient than the cement-hydrated lime con- 
struction. In this comparison the puzzolan cement is at an economic disadvantage 
because of the long freight haul. 

CLAY IN CONCRETE. 

The object of the tests was to compare the effect of clay in reducing permeability 
with the effect of equivalent weights of extra cement. 

1 14 



ry^CONSTKU __ 

LKemcjneeking 



iCTJSNATJ 



IMPERMEABILITY TESTS ON CONCRETE. 



The clay used was a white, pure clay from Georgia, Intended to represent high- 
grade material in colloidal properties. Approximate quotations of prices, delivered in 
New York, gave the cost as very nearly -equal to that of Portland cement, weight for 
weight. The tests, therefore, afford a direct comparison of costs of the two pro,. 
v I waterproofing, assuming that the use of clay involves no extra cost in mixing the 
concrete. 

Plain concrete of two percentages of cement, to per cent, and 11 per cent., were 
selected as the basis of the tests, the total percentages of fine material in the dry mix, 
45 per cent., remaining constant. The percentages of clay used were based on the 
weight of the sand and replaced the stated percentages directly by weight. The 
percentages of clay selected were 5, 7*5, and 10 per cent. For comparison, a series of 
specimens was made in which extra cement replaced the stated percentages of sand in 
the same manner as the clay; also blanks or specimens containing no clay or extra 
cement. 

The casings of neat cement in which the specimens were enclosed for testing were 
not as perfect as are usually secured, and permitted a small leakage between casing 
and specimen in a few instances. The water appeared at the edges of the specimens 
and could not be separated from that coming through the concrete. In tabulating the 
results these defectiye specimens, as determined by the judgment of the observer, were 
omitted. 

Table II. shows, as in previous tests with clay, a marked decrease in permeability 
over plain concrete, but as compared with the extra cement there is no practical 
advantage. Both processes give impervious concrete at 80 lb. pressure. It is of 
practical value to note that the concrete of ordinary sand and gravel containing 13-5 
per cent, cement was impervious at a pressure corresponding to 185 ft. head of water. 



TABLE II. — Permeability and Strength Tests of Concrete, Effect of Clay. 







Proportion 


by weight. 


Clay, 


Leakage 
in grams. 


Compara- 
tive 

strength, 
lb. per 
sq. in. 


Density. 


Water, 












Cement. 


Clay. 


Sand. 


cent. 
Gravel. 


Pres- 
sure, 
40 lb. 


Pres- 
sure, 
80 lb. 


cent. 


Group A . . 


1 
r 
1 
1 




0-18 
0-26 
o-35 


3-5° 
3-32 
3-24 
3-15 


r 5-50 

5-50 5 

r 5-5° 7-5 

5-5° 10 


6 





73 
3 
9 



770 

910 

1,110 

945 


0-789 
0-782 
0-768 
0-770 


9'3 
8-i 
9-6 
9-2 


Group B . . 


r.r8 
1-26 
i-35 







3-32 
3-24 
3-15 


5-5o 
5-5° 
5-50 



3 



2 
10 



1,130 I 0-807 
1,290 o-8oo 
1,265 0-780 


7-9 

8-3 
9-2 


Group C . . 


11 

i-i 
i-i 
i-i 




0-17 
0-26 
o-34 


3 - 4° 
3-23 
3-14 
3-06 


5-50 
5-5° 5 
5-50 7-5 
5-50 10 


37 





128 


Trace 


800 0-775 
880 ! 0-780 
905 0-772 
905 0-777 


9-7 
93 
9-3 
9-8 


Group D . . 


1-26 

1-35 
1-44 







3*24 
3-15 
3-06 


5-50 
5-50 
5-5° 


3 



Trace 


10 

17 


1,290 1 o-8oo 
1,265 0-780 
i>395 °'79^ 


8-3 
9-2 
10-4 



Sand, Cow Bay passing o-2-in. sieve : gravel, Cow Bav. between 1-75 and o-2-in. sieves. 

Portland cement ; tensile strength, 1 : 3 Ottawa sand, 28 days, 329 lb. per sq. in., sp. gr. 3-18, Thru No. 2oc-mesh 
sieve, 76 per cent. 

White Georgia clay passing No. 30 sieve. 

Compare Group A with B, C with D, Groups A and B based on 10 per cent, of cement. Groups C and Don 11 per 
cent, of cement. Clav replaces stated percentages of sand based on the blank. Age at testing, 28 days. Duration of 
permeability test one hour at each pressure. Leakage reported for last 10 min. Three specimens in each average usually 
Specimens cylinders 8 in. in diameter, 6 in. in length. Compressive specimens, cylinders 6 in. in diameter, 12 in. in length 
One specimen in each test. 

There is a trivial discrepancy, o"oi per cent., in the percentages of excess cement 
in two of the tests in group D as compared with the percentages of clay in the corre- 
sponding tests in group C. It will be observed these tests in group I) were broi 
down from group B, these specimens containing so nearly the right percentage- 
cement that new tests were not required for comparison with group C. 

Density. — The clay slightly decreased the density in the 10 per cent, concn 
slightly increased it in the 11 per cent, concrete. The excess cement slighth 

D2 



JAMES L. DAVIS. 



(CONCRETE 



TABLE III. — Permeability Tests of Mortar, Effect of vf.ry Fine u m vr. 







Leakage 


n grams. 




Fineness. 


Specific gravity. 


Brand 


















Xo. 


Normal 


Cement 


Sifted 


Cement 


Sieve 


Number 








pressure, 


pressure, 


pressure, 


pressure. 


100. 


200. 


Normal. 


Sifted. 




40 lb. 


80 lb. 


40 lb. 


80 lb. 










i* 


3 


22 


3 


33 


96-5 


79-8 


2-16 


3 - '3 


2 




25 




2 


93*5 


74-6 


3-17 


.3-13 


3 




-"' 




Trace 


97-6 


89-2 


3-08 


3-05 






331 




81 


94"7 


84-9 


3-16 


3'H 






^7 




Trace 


92 - 3 


78-9 


3-13 


3-12 


6 




31 




2 


91-3 


79"4 


3-14 


3-n 


7 




5 







95"4 


75-° 


3-19 


3-17 


8 




6 




Trace 


95-3 


8i-o 


3-18 


3-i6 


9 




7i 







91-0 


73'° 


3-10 


3-09 



* Retained on No. 200 sieve, 2,163 grams leakage at 40 lb. pressure. 
Proportions 1 : 4 by weight. Sand, Cow Bay graded so as to be permeab'e. 
Age, 28 days. Duration of test one hour. Leakage reported for last 10 min. 
Specimens, 2-in. cubes enc'osed in neat cement casings. 

Five or six specimens in each average, except for brand No. 7, in which throe specimens wtre used. Temperature c 
water 63 to 68° F. 

the density in both the 10 and 11 per cent, concrete, with the exception of the 10 per 
cent, increase in the 10 per cent, concrete. The maximum increase with both the 
10 and 11 per cent, concrete was with 5 per cent, excess cement. 

Strength.— Strength was tested only incidentally, the material used for the density 
tests being utilised to produce a single 6x12 in. compression cylinder of each mix 
for testing at 28 days' age. The clay gives increased strength over the blanks, but a 
smaller increase in all cases than the corresponding excess of cement. 

It is noticeable that the clay gives better results in the leaner concrete. This seems 
to indicate that the clay acts simply in a manner similar to ordinary very fine aggre- 
gate, for it is well known that lean concretes are benefited in strength by the addition 
of fine material, such as loam and dust, while rich concretes are not. 

Notes on Clay. — It should be remembered that these comparisons are based on the 
assumption that no extra cost in mixing the concrete is involved in the use of the clay. 
This assumption is undoubtedly in favour of the clay, as special appliances for intro- 
ducing it would be necessary. In these tests the clay, which was in a comparatively 
dry and lumpy condition, was pulverised and sifted to pass a No. 30 sieve. Fifty-four 
per cent, passed the Xo. 100, and 15 per cent, the No. 200 sieve. Should it be found 
necessary to adopt this method in practice, the process would involve considerable 
expense. A less expensive method, if found practicable, would be to add the clay to the 
mixing water. 

Should it be found that common brick clay would serve the purpose, this material 
could be obtained for about $3 per ton, or about three-eighths the cost of cement. 
This advantage would be partially offset by the mechanically combined water in the 
clay. Clav as taken from the bank ordinarily contains 20 to 40 per cent, of 



TABLE IV. — Permeability Tests of Concrete, Variation of Leakage with Pressure. 









Pressure and 






^atio of leakage 


s _ 








leakage. 






Sand. 


Stone. 


Proportions 
by weight. 




























20. 40. | 60. 80. 


IOO. 


40-20. 


60-20. 


80-20. 


100-20. 


Cow Bay 


Limestone 1-75-0-2 in. 


I : 3-50 : 5-83 


3 6 


13 -i 




2-00 


4"33 


7-67 




Cow Bay 


Gneiss 1-50-1-0 in. 


1 : 3-50 : 5-66 


s iq 


35 47 




3-8 


7-00 


9-40 




Cow Bav 


iss 1-50-0-2 in. 


1 : 3'5° : 5'66 


•, 64 


109 157 


J"i 


2-21 


3-76 


5-42 


7-07 


Crushed Gneiss 


Gneiss 1-50-0-2 in. 


1 : 3-60 : 5'66 


55 126 


22<> ilil 


496 


2-29 


4-00 


6-57 


9-02 


Cow Bav 


Gravel t'75-0'2 in. 


1 : 3-50 : 5'5C 


14 27 


SI 80 


132 


I"93 


3-64 


y~- 


9 - 44 


Sha'e and Cow Bay 


Shale i-Js-o-2 in. 


i = 3-53 . 5'72 


14 22 


48 80 




i-59 


3-43 


5'7J 




Average 












2-30 


4-36 


6-75 


8-51 



Specimens cylindi rs, 8 in.^diameter, 6 in. length. 

Age at testing, 28 days. 

( rin. 11 1 , Portland, 81 per cent, passingJNo. zoo sii vi 

All sand passed a 0'2-in. si( V( . 

Pressures in lb. per sq. in. 

Il6 



[JllllillSS IMPERMEABILITY TESTS ON CONCRETE. 

mechanically combined water. This amount can be greatly reduced by air drying, but 
clay is very hygroscopic and may absorb as much as to per cent, oi il .. ighl of water 
from the atmosphere. 

Conclusions. — (i) Clay added to ordinary concrete gives beneficial results in 
permeability and strength, with no practical effecl in density. 

(2) Compared with an equal excess of cement by weight, clay gives no advantage 
of practical importance in permeability or density, and results in a loss in strength. 

(3) Both processes give impermeable concrete under 80 11). pressure. 

(4) If the use of clay is practicable on a working scale, its possible economic use 
under two methods is evident : 

(d) By mixing with the cement at the cement mill. The mixed material would 
have to be sold about 20 per cent, cheaper than ordinary cement. 

(b) By mixing in the field in localities where the cost of cement is high and clay 
can be obtained very cheaply. 

Subsequently to the above tests another series was made in which blue New York 
brick clay was substituted for the white Georgia clay. The results confirm the 
earlier tests. 

EFFECT OF VERY FINE CEMENT. 

Tests on mortar specimens were made using cement in its normal condition, 
parallel tests being made using portions of the same samples of cement sifted through 
the No. 200 sieve. A single test was made using the residue on the sieve. Nine well 
known brands comprised the series. 

The marked decrease in permeability, as shown by the accompanying Table III., 
resulting from the sifted cement shows that as in strength so in permeability the 
finer particles only are efficient. Extremely fine grinding may be of even more import- 
ance for its effect on impermeability than on strength. 

ADDED CEMENT AS A FILLER. 

The writer designates such finely divided materials as hydrated lime, clay, puzzolan 
cement, sand cement and very fine sand, for want of a more scientific name, as pore 
fillers. The preceding and other tests not described here have demonstrated that such 
substances may be used to produce highly impermeable concrete. The same result 
can, however, be obtained by the use of an extra amount of Portland cement, at less 
cost usually than by any of the special materials, and in all cases with an increase in 
the strength of the concrete over the other materials. For impermeable construction 
concrete should contain not less than 45 per cent, of combined fine aggregate and 
cement. With ordinary aggregates 15 to iS per cent, of the entire dry mixture should 
be cement unless the resisting walls are several feet in thickness. 

In all the preceding tests the smooth top and bottom surfaces of the specimens 
were chipped off. The surface formed against smooth forms is very highly effective 
against permeability if unbroken. Offsetting this important matter in practical work 
we have the usual necessity of depositing the concrete in successive layers with the 
possible attendant formation of planes of stratification parallel to the water pressure. 
Leakage in this direction, unless the concrete is of such a wet mixture and the con- 
struction so continuous as to prevent the formation of such planes, may be many times 
greater than that due to perpendicular pressure. In one test on 1 : 27 : 6-3 concrete 
the excess of leakage parallel to the bedding planes was 70 per cent. 

VARIATION OF LEAKAGE WITH PRESSURE. 

In this series the aggregates included quartz gravel, crushed limestone, gneiss 
and shale. 

The fine aggregate, included both natural silicious sand and screenings from the 
coarse aggregates. In one set a half and a half mixture of natural sand and screen- 
ings was used. 

The series, therefore, represents a wide range in materials. Each of the six 
consisted of three specimens. Nearly every specimen was tested at each of 
pressures. The specimens constituted the blanks from a larger series <>f perm 
tests made at 40 and So lb. pressure in which certain chemicals v 
their waterproofing properties. It is unnecessary to describe the larger 

II- 



JAMES L. DAVIS. 



[CQNCREXEJ 



The present tests were made by subjecting the specimens to a second series ef 
pressures of greater range than the original pressures. Following the first tests the 
specimens were allowed to drain about 2 hours. Pressure of 20 lb. was then applied 
and raised to 40, 60, 80 and 100 lb. at 30-min. intervals. The total leakage for the 
last 10 min. of each period is used in this study. 

Observations early in the tests showed that for this series fairly uniform rates of 
leakage were established within 30 min. after pressure was applied. 

The average results on each set of three specimens are given in Table IV., and 

averages for the entire series by the accom- 
panying curve. 

The range in pressure was sufficient to 
cover all heads up to 230 ft. The general 
conclusion is reached that leakage increases 
more rapidly than pressure. In any practical 
case, having the leakage determined by a 
test within the range of pressures given 
above, the leakage at any other pressure may 
be estimated by referring to the curve. 

Lean concrete was used in order to insure 
measurable rates of leakage throughout the 
series. 

The leakage was higher in this series of 
tests than in the original tests on the same 
specimens. The average increase for the 
eighteen specimens was 29 per cent, at 40 lb. 
and 12 per cent, at 80 lb. pressure. This 
indicates that raising the pressure enlarges 
the water passages. It is probable that under continued action the rate of leakage 
would decrease in the usual manner. 



_>~I0 

c c a 
o=> " 

«£-, 

OQ- r 

JJ5 4 

CM 

o-h 3 
.9 v 2 



20 "~ 40 60 SO 

Pressure m Pounds per Square Inch 

Variation of Leakage through Concrete 
with Pressure. 



100 



118 



f g r constructional} 



CONCRETE ORNA MENTA TIUN. 




THE USE OF CONCRETE 

FOR ORNAMENTATION 

IN AMERICA. 



That concrete can be successfully applied for ornamental use in public parks, gardens, 
etc., nvill be seen from the subjoined particulars of some nvorks carried out for the 
municipality of Chicago. We are indebted to "Concrete Cement Age," U.S.A., for 
our illustrations and details, abstracted from an article by Mr. Marc. N. Goodnoiv. —ED. 



In the 
a very 

can be 
pieces 



laying - out of the grounds in the Chicago Parks, U.S.A., concrete played 
prominent part, and these parks form a very striking example of what 
done by the use of concrete in artistic buildings, ornamental ground 
and flower receptacles. 

Sherman Park. — The en- 
trance to this park is marked 
by six heavy reinforced concrete 
pillars or gate-posts of orna- 
mental design. Just inside the 
gates is a pebble concrete arch 
bridge spanning a lagoon. The 
top of the bridge, or guard 
rail, is capped with concrete 
slabs made in sections. Two 
such bridges are to be found in 
this park. 

Fuller Park — This park 
has a very fine recreational 
building of three stories, with a 
fountain court and corridor or 
cloister of four sides in con- 
crete. There is also a very 
large swimming tank and bath- 
ing house. This swim mini; 
tank is lined with white terra- 
cotta. 

Washington Park. 
Among the many interesting 
features in Washington Park 
are numerous urns, fountains, 
and concrete was lare 

Concrete Flower Urn. . , 

Washington Park. Chicago, U.S.A. in the COnstrUCtlO and 




119 



CONCRETE ORNAMENTATION 



[CQNCftEJEJ 



ornamentation of the administration building in this park. Our illustrations 
show some ornamental flower-pots and pedestals. In the construction of these 
pedestals a mixture of i part limestone screenings, 2 parts pink granite screen- 




Concrete Posts. 
Sherman Park, Chicago, U.S.A. 




Pebble Concrete Bridge. 
Sherman Park, Chicago, U.S.A. 



ings, with 1 pari cement to 2 parts of limestone and granite was used. This 
mixture was placed inside two sections of a gelatine mould cast from the 
object to be reproduced and hound firmly together by rope. 



f j, coNyi "win lONAi.i 

I A. fcNOlNt.fcRlNG — J 



IN AMERICA. 



The upper basin is of the same material. No terra-cotta lining was used 
in constructing the howl, but it was reinforced at the top with wire netting and 
4-in. rods spaced 10 in. apart. A i-in. finishing coal was later on applied 




Inner Couit, Recreational House. 
Fuller Park, Chicago, U.S.A. 



' «» ■> \ "UU... ;., ' .'. „w t i 



BIBIBiBWI 



* "V 





Concrete Swimming t'col. 
Filler Park. Chicago, U.S.A. 

composed of 2 parts sand, 1 part cement and l\ gallons of a watcrpn 
compound called Hydrolite to each barrel of cement. 

Wading pools and swimming tanks abound in these parks am' 
times surrounded with concrete benches. 

Among other remarkable features of these parks we would men 

i 2 1 



CONCRETE ORNAMENTATION 



iCQNCBETEl 



crete breakwater in Jackson Park. The entire body of the breakwater, which 
also acts as an inlet to a chain of inner lakes, as well as the heavy, short 
pillars and double bar railing, are of reinforced concrete. In this park, also, 




Pebble Concrete Bridge. 
Sherman Park, Chicago, U.S A. 




Reinforced Concrete Recreation Building. 
Fuller Park. Chicago, U.S.A. 



there is a golf course with numerous fountains of running water east in 
concrete. These fountains are 2 ft. 6 in. in height and are reinforced about 
the basin and pedestal and surrounded at the base by a wide platform of 



fo r COHSTUUCn 

Lft-ENGTNEEJ?1NG 



lONAtJ 



IN AMERICA 



concrete pavement. The interior of the basin has been finished with a coating 
of cement, no terra-cotta being used to line these small fountains. 

The use of concrete has hern found to be particularly advantageous in this 
park on account of the dampness about the heavy foliage where buildings are 
of ten erected. For this reason alone, the writer of the article states, the wide- 
spread use of the material is rapidly increasing, and as time goes on all the 
frame construction which rots away will be replaced by permanent concrete 
structures, upon which time and damp have no effect. 




Concrete Flower Pots. 
Washington Park. Chicago, U.S.A. 



THE CONCRETE INSTITUTE. 




[CONCRETE! 



RECENT VIEWS ON 
CONCRETE AND REIN. 
FORCED CONCRETE. 



THE CONCRETE INSTITUTE- 



It is our intention to publish the Papers ana Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available for reference purposes. 

The method "we are adopting, of dividing the subjects into sections, is, tve believe, a 
nevj departure. — ED. 

THE CONCRETE INSTITUTE. 

ACTION OF ACIDS, OILS AND FATS UPON 

CONCRETE. 

By W. LAURENCE GADD, F.I.C., M.C.I. 
7 he following is an abstract of a paper read at a meeting of the Concrete Institute on 
December 12th, 1912. In connection with the paper the author gave numerous tables 
setting out the tests made by him, but zee only reproduce tables A, B, and F here. A 
discussion followed, of which a summary is also given. 

GENERALLY. 

Neither cement nor concrete will withstand the action of hydrochloric, nitric, and 
sulphuric acids. They decompose and dissolve the constituents of cement, even in 
dilute solution. Even a weak acid, like carbonic acid, has a distinct action upon 
cement, which, suspended in water, can be practically entirely carbonated by passing 
a current of carbon dioxide into it. 

The action of organic acids, such as lactic and butyric acids, tannic acid, tartaric 
and citric acids, and acetic acid or stale beer, is not so marked; but it is very probable 
trat the whole of the series of higher fatty acids will be detrimental to concrete. 

The tendency of organic acids to combine with carbonate of lime is much less 
than with hydrate of lime, and it follows that an acid which would be dangerous in 
contact with green concrete might be perfectly harmless in contact with old or in- 
durated concrete. Thus, stale beer has a distinctly detrimental action upon new work, 
but once the concrete has indurated by exposure to air for some time, the acid of 
sour beer has little action upon it. 

Fresh beer has, itself, a weakening action on green concrete ; but the deteriora- 
tion in this case is due to the sugar and other organic constituents of the beer, and 
not to the action of beer acids. 

TABLE A. 
Tensile Strength (lbs. fer square inch.) 
Xeat. 
3 Days. 7 Days. 28 Days. 

Kept in water 630 765 1,020 

620 730 g6o 



Sand (3:1). 

7 Days. 28 Days 

340 4-*5 



Kept in beer 



124 



625 

620 
560 

590 



747 



gqo 



Plunge pat — Sound. 

710 810 

675 75o 

692 780 

Plunge pal — Failed. 



300 



360 



g^HBgg ACTION OF ACIDS, ETC., ON CONCRETE. 

The test pieces were gauged with water in the usual way, and after twenty-four I 
in moist air were immersed in water and beer respectively until due for breaking. 

One of the commonest forms of acid action to which building material i 
is that of sulphuric acid, derived by oxidation from the sulphurous gases present in 
the atmosphere of large towns. This is noticeable on Portland stone, but appears to 
be less marked on concrete buildings, possibly for the reason that the surface pore-, 
of concrete become closed with a deposit of calcium sulphate, which affords protection 
from further action of the acid. 

Lactic acid is produced by the fermentation of milk, brought about by the micro- 
organism Bacterium lactis, and is a possible acid to come in contact with concrete 
structures in farm buildings. The action of this acid is confined to combination with 
calcium hydrate, forming calcium lactate (Ca (C :j H-,0 :! ), + 5H,0). This salt is soluble 
in water, and in wet situations would be readily leached out of concrete in which it 
was binned, so that the deleterious effect of lactic acid would consist in the gradual 
removal of the lime hydrate, which plays an important part in the induration of 
concrete. For practical purposes, it is probable that this action would be very small. 

The following tests show the effect of prolonged immersion in a solution of lactii 
acid, prepared by fermenting milk, and removing the curd : — 

TABLE B. 

Mortar 4 : 1 (ordinary building sand). 

Test pieces 1 day in air, 27 days and 3 months in the whey and in water 
respectively. 

Tensile Strength. Crushing Strength. 

28 Days. 3 Months. 28 Days. 3 Months. 

In whey 430 470 4, 700 6,700 

440 470 4,<;oo 6,000 

435 470 4,800 6,350 

In water 400 495 4,600 

410 480 4,750 

405 4_8_7 4,675 

This is, of course, a much more drastic test than would be at all likely to occur in 
practice, but the results do not disclose any marked deterioration caused by the 
lactic acid. 

Concrete vats would appear to be suitable for tanning operations, and the possible 
action of tannic acid becomes of importance. This acid, of which gallotannic acid 
(C 14 H ln O !P ) may be taken as a type, is again an organic acid which combines with 
calcium hydrate to form calcium tannate, but as the combining weight of tannic acid 
is high — sixteen parts by weight combining with only one part of calcium — the 
probable action is not very serious. 

Various tests have been carried out in order to ascertain the effect of gauging 
with a solution of tannic acid (two grammes per litre), and, for comparison, test 
pieces of the same cement were also made in the usual way, gauging with water 
only. 

It was found that the test pieces gauged with tannic acid solution gave lower 
tensile and crushing strains, but the difference is not sufficient to mark any great 
deterioration. 

OILS AND FATS. 

Proposals have of late been made, particularly on the other side of the Atlantic, 
to incorporate a certain small amount of oil or fat with concrete, with the object of 
giving the same dustless, waterproof, and other qualities. \\ 'hat we might almost 
call the natural instinct of the concrete worker has, however, always led him to 
avoid oil or grease as far as possible, and he has been right. 

Many oils and fats react chemically with the cement constituents, and in this 
must be placed the whole of the oils and fats of animal or vegetable origin. 

These substances consist of the glycerides of various fatty acids, such as 
palmitic, and oleic acids. 

The glvcerides of the fatty acids, which constitute the neutral 
animal or vegetable origin, are readily decomposed, or saponified, b; 

'^5 



THE CONCRETE INSTITUTE. ICbNckJfcl ta 

and metallic salts, and by all alkalies, including calcium hydrate, which we know is 
3 constant product in cement or concrete which has been gauged with water. The 
result of this saponification is the decomposition of the oil with the formation of a 
metallic or alkaline salt or soap, and the liberation of glycerin. 

Thus, tallow is saponified by calcium hydrate, according to the following 
equation : — 

2C :t H,(C ls H :t5 2 ) 3 +3Ca(OH) 2 = 2C :( H / ,(OH) :f +3Ca(C ) sH,,0 2 ) 2 . 
Tristearin (tallo\v) + calcium hydrate = glycerin + calcium stearate (lime soap). 

Calcium stearate is a whitish, friable material, insoluble in and immiscible with 
water ; whilst the lime soaps of other fatty acids commonly occurring in oils and 
fats are slimy and sticky substances which, although water repellents, do> not, so 
far as the author's experiments show, render concrete less permeable to water, and 
decidedly reduce the tensile and crushing strength. 

By this process of saponification, which takes place rapidly under the influence of 
heat and more slowly in the cold, cement or concrete will certainly be injured by the 
admixture of any animal or vegetable oil or fat; and if the concrete be green or new, 
there is some liability of damage being done to it by mere contact, such as might 
occur from constant drippings of oil upon it. 

Calcium carbonate has not the power to saponify neutral oils or fats, so that oil 
in contact with indurated concrete, in which the calcium hydrate has been largely 
converted into carbonate,, would have little deleterious action. 

Mineral oils a-rrd greases, which are hydrocarbons, are of a different constitution 
from that of the animal and vegetable oils, and are incapable of saponification. They 
have, therefore, no injurious action from this particular cause, although they weaken 
the strength of concrete for physical or mechanical reasons. 

This is experimentally confirmed by a series of tests on sand mortar 3:1, in 
which various oils and fats were incorporated to the extent of one-tenth of the weight 
of cement used. 

The oils and fats used were vaseline, cvlinder oil, lard, cotton seed oil, and colza 
oil. 

The tests were for periods of seven days, one, three, six and twelve months. 

The results of the tests showed that the vegetable and saponifiable oils, cotton 
seed and colza, are absolutely destructive to concrete, and that the mineral oils, which 
are not saponifiable, reduce the strength very materially when mixed in small propor- 
tion with the mortar. 

When testing samples of cement for tensile strength, the author observed that 
many operators use colza oil for the purpose of greasing the briquette moulds. The 
film of oil which remains, or should remain, on the moulds is, of course, very thin, 
but colza oil cannot be considered a suitable oil for the purpose, seeing that it has so 
great an action upon cement. Briquette moulds should be oiled with mineral oil, or 
a mixture of heavy mineral oil and paraffin. 

In order to test the waterproofing qualities of oil-mixed concrete, flat slabs of 
similar mixtures to the above were made in a standard manner, and, after twenty-eight 
days, were submitted to percolation tests by subjecting them to a water pressure of 
50 lb. per sq. in., in such manner that the water forced through the slabs could be 
collected and measured. The following table sets forth the results obtained : — 

TABLE F. 

Slabs kept 28 days in water before testing. Size of slabs — iox 10x3 in. 

Area subjected to water pressure — 16 sq. in. 

Water Percolated through the Slabs. 

Oil added. Litres per Hour. 

None (cement only) (1) 4'; 

(2) i;'7 

Vaseline (1) 134C0 

(2) 34Q'o 

Cylinder oil (il 6q.s'o 

(2) 26V0 

Lard - (1) Slab broke 

(2) 
Cotton-seed oil (1) 

(2) 41'2 

Colza oil (1) Slab broke 

U) 
l 26 



(HIBmEBB action of acids, etc., on concrete. 

It is to be noted that these slabs were not intended to be made absolutely water- 
tight, the object being to obtain a comparison. Leighton Buzzard sand was therefore 
Used, and the results show that under identical conditions sand mortar without any 
addition of >oil was more watertight than with any of the oils or fats tried. The 

addition of lard, colza, and cotton-seed oils to the extent of less than 2*5 per cent, on 
the weighl of the concrete prevented the slabs from setting properly even after twentv- 
eight days, and they were unable to withstand the water pressure placed upon them. 

In order to test the effect of oils upon concrete gauged with water in the usual 
way a number of briquettes were prepared, consisting of four parts of ordinary build- 
ing sand to one part of cement ; and after twenty-four hours in moist air I lux- were 
immersed in various oils for periods of one, three, six and twelve months, at which 
dates the tensile and crushing strengths were ascertained. 

A further series of similar test pieces was prepared, but in this case the briquettes 
and cubes were allowed to mature in air for twenty-height days before they were 
immersed in the oils. 

These tests again bring out the destructive action of saponifiable vegetable oil, 
the test pieces immersed in cotton-seed oil being reduced to mud in less than three 
months; and although the mineral oils and turpentine had much less marked effects, 
they nevertheless materially reduced the strength of the concrete immersed in them. 

The broken briquettes, which had been immersed in oils for twelve months, were 
freed from the sand, as far as possible, by sifting, and from adhering oil bv repeated 
extractions with ether, and then submitted to chemical analysis. 

There were five samples, A, B, C, D, E. The first four had been one month 
in air and twelve months in oil. Sample E was only one day in air before immersion 
in oil. 

The results showed that concrete in contact with certain oils suffers chemical 
change by the combination of the liberated calcium hydrate with the fatty acids of the 
oil, as much as 32 per cent, of oil being combined in a period of twelve months, when 
green concrete is immersed in cotton-seed oil. 

This amount of oil in combination as calcium oleate and stearate is quite sufficient 
to account for the disintegration of the concrete. 

In parallel cases of briquettes immersed in cotton-seed oil after one month's 
induration, and after one day only in air respectively, the action of the oil was much 
less marked in the former than in the latter, due to the fact, as mentioned earlier in 
this paper, that fattv acids do not react with calcium carbonate. 

CONCLUSIONS. 

The conclusions drawn by the author from theoretical and experimental data 
are' : — 

i. That the addition of oil or fat, of any kind, to concrete results in a weakening 
of the strength. 

2. That animal and vegetable oils have a direct action on green concrete, and in 
time will bring about its destruction. 

3. That indurated concrete is less liable to be attacked by oils and fats. 

4. That oil-mixed concrete is not rendered more waterproof. The least permeable 
concrete is, in the author's opinion, a dense mortar in which the aggregate is properly 
graded to fill the voids. 

DISCUSSION. 
The President : One thing Mr. Gadd has proved is this, that the addition of any extraneous 
matter to Portland cement does not improve its strength. It is well known that where acids 
come into contact with concrete, then destruction is bound to take place sooner or later. In 
amplification of this paper Mr. Wells stated he had made some experiments six or seven years 
ago as to the action of creosote upon concrete. He was designing a tank to contain creosote, 
and wanted to find out what the action of creosote would be upon concrete which had 
kept under air for six months, three months; five to one concrete, three to one s; 
and neats ; and in every instance where it has been kept in creosote for 18 months die strengni 
was higher than when it was kept in water. In the case of neat cement, after 18 month 
test for crushing amounted to 1,163 t<" ls a s( l- ft., and g'46 tons a sq. in. I 
under normal conditions — that is to say, anywhere ranging from 40 to 60 degrees Fahrenh* 
and during the whole of the period in the neat cement tes 3 the 1 



THE CONCRETE INSTITUTE. [CONCRETE] 

at all, and it had only entered to about one-eighth of an inch, except where one sample was 
made with a very soft and porous stone, where it went right through. But where the same 
tub- were then placed in a chamber where the creosote was heated to 120 degrees in less than 
14 days it went clean through the neat cement. 

Mr. D. B. Butler, Assoc. M. Inst. C E., F.C.S. (Member of Council C.I.) : Only those who 
have had occasion to undertake research of this kind can realise the immense amount of work 
involved in a paper as the one prepared by Mr. Gadd. 

It is a little peculiar that the very first substance or liquid mentioned in the Taper is 
beer. As a rule the effect of beer on concrete is very indirect. Hut he would like to ask, 
referring to the beer tests, as to what effect the beer had on the setting of the cement. 
Mr. Gadd in most of his experiments only gives the average of two cubes or briquettes on each 
date, and in referring to Table B it will be seen there that the result at three months in whey, 
if only one briquette should have been taken instead of two, the result in the one instance 
would have been 6,700, and in the water 6,800, practically the same; so it shows really the 
necessity in all these experiments for taking a fair average ; two is hardly enough. 

With regard to the tests where the cement was gauged with tannic acid, comparative tests 
are given with tannic acid and water. In this experiment the test pieces in each case were 
mixed wdth a solution of tannic acid. That seems to be scarcely as practical as it would have 
been if the test pieces had been made with water in the ordinary way and immersed in a 
solution of tannic acid. Briquettes of concrete are not as a rule gauged with tannic acid, but 
sometimes, as shown, it is subjected to the liquids from tanning. 

He quite agreed with Mr. Gadd's remark where he refers to what he calls the natural 
instinct of concrete workers in avoiding oil or grease in any w : ay. We know r that in moulding 
briquettes and moulding test pieces we oil our moulds. Do we oil our moulds to make the 
cement stick to the moulds or otherwise? So it seems a very fair answer to mixing oil of any 
kind with cement. 

Regarding the results of the test of the various vaselines and oils mixed with cement, it 
would be interesting to know how the author managed to mix vaseline and oil with the 
concrete in those small proportions and the method in which he did that. 

Referring to the colza oil tests, it is a little curious that the seven days' results show a 
small crushing strength ; the one month and three months' show no strength at all ; then they 
go on again, and in six months' and twelve months' they have gained some strength again. 

Regarding the percolation tests, some further particulars are needed. Some twenty-five 
years ago Mr. Faija in his forced percolaton of sea-water through concrete, used half-inch 
briquettes, composed of three to one sand, a brass clamp was fixed top and bottom of the 
briquette, to which was attached a screw nozzle to the pipe, and then same was attached to a 
water tank 15 ft. above, so that a 15 ft. head of water was obtained forcing through this 
briquette, and after a time it was found the percolation ceased entirely owing to the blocking 
up of the pores both with sea water and fresh water. 

Regarding the test pieces immersed in various oils compared with water. It is certainly 
rather drastic to immerse a briquette into absolute oil and turpentine. But it is curious that 
the tensile strength of the cotton-seed oil is absolutely nil in each case, whereas the crushing 
strength varies from goo lb. to 1,700 lb. at various dates. 

The same irregularity occurs in the tests where the cotton-seed oil at one month gives only 
an average of 62 lb. tensile, but an average of 2,675 crushing. As a rule, the ratio between 
tensile and crushing is somewhere about ten to one — that is, the crushing is about ten times the 
tensile, and, curiously, in this case it is roughly only about a one-hundredth part. 

Regarding Table F, it would be interesting to know if in addition to the analyses of the 
briquettes immersed in the various kinds of oil, showing the combined oil and combined water 
with extracts of the oil- and sand, whether a briquette had also been analysed which had been 
immersed in water only showing the amount of combined water in the briquette. 

With reference to sample K, which was only kept in air one d.n before- immersion for 
twelve months, whereas the other samples had been kept in air for one month, this seems a 
little peculiar, and it would be interesting to know why tin- was done. 

Mr. A. Alban H. Scott, M.S. A. (Member of Council CI.) : There is rather a curious co- 
incidence in the tests with oils and fats. The crushing strength of the cement at -even days 
is about 4,000, and at twelve months it is almost all the way through just double that strength. 

With regard to the percolation of water through the cement, a verv large reinforced 
concrete structure had been put up about eighteen months ago, and it had very slight leakages 
at tir>t, but all those pure- are tilled up, and he believed that is the usual experience with 
concrete subjected to a head of water, 1 li.it it dc--, it properly made, become eventually 
more or le>s watertight, assuming, of :cmr-e, it is fair average concrete for that class Of work. 

128 



(lllffllllaBJS ACTION OF ACIDS, ETC., ON CONCRETE. 

Bu1 an interesting thing which the client did in that case was thi> : he threw oatmeal into the 
water, and whether it wis the oatmeal that gradually, with the very slight movement of « 
actually tilled up the points of leakage, or whether it was due to the action of the c< 
is Questionable. 

Mr. R. W. Vawdrey, B.A., Assoc. M.lnst.C.E. (Member of Council C.I. ), asked the author to 
what extent lie thought that the weakening of the concrete, either tension or compression, was 
due to the actual diminution of the size of the concrete. In some cases, at any rate, he 
assumed, where the action was very marked, as in the case of colza oil, on some of his 
briquettes, there was an actual diminution in the size of tin- block. Apart from that, how- 
ever, there must be a considerable proportion of the interior of the block or briquette that is 
quite unaffected. It would be rather interesting to know what area of the cube or briquette 
w.is actually atTected by the oil. In some cases it need not be necessarily affected throughout 
i'- depth. 

Mr. Perclval M. Fraser, A.R.I.B.A., M C.I., in asking whether any volatile oils had been 
under discussion in the paper, stated that petrol in reinforced concrete is so much to the fore 
in these days that a little experiment in connection with the two might be quite interesting. 

Mr. Frederick Hingston (M. Quantity Surveyors' Association) thought Mr. Gadd's paper 
most opportune, because at the present time there are in the market a number of patent 
preparations or compositions which if added to cement are supposed to make it waterproof. 
These patent preparations doubtless include fatty acids. It would be of vtilue to know 
whether the lecturer considers the addition of those materials, that can be seen upon the pages 
of all the professional journals, is detrimental to cement and concrete. 

Mr. Q. C. Workman, in his opening remarks, inquired whether there is any danger in 
mixing soap with the concrete, assuming that it has the beneficial effect of making it water- 
tight, as recently shown in the American Press. 

Referring to the whole trend of this paper, he was very pleased to see that it absolutely 
confirms what he has always held to be a rule for concrete engineers to work upon when dealing 
with any of these greases or acids — namely, that it seems, by various tests which have been 
made that mineral oils and greases which are hydro-carbons do not seem to affect the concrete, 
but animal and vegetable oils seem to affect it. He had always held it as a very broad rule 
that in dealing with concrete which has to contain any animal or vegetable oil, it is dangerous, 
if the concrete is to resist the effects of mineral oils cold — he had no knowledge about them 
hot. All the information he had been able to gather from tests and reports fjrom 
various sources on the subject, and all he had read, seemed to be borne out by Mr. Gadd's 
experiments, which are certainly of great value, and which, no doubt, will be very useful 
to reinforced concrete specialists in particular, seeing that they are continually coming into 
contact now with the question of reservoirs and pipes which have to contain fats and acids; 
and, especially with regard to naphtha and various other mineral oils, he was inclined to think 
there was no danger in making the reinforced concrete reservoirs and pipes to restore this 
material, if cold. In spite of all the evidence on the subject, it is very strange to have to 
say that there seems still to be a certain amount of doubt. He had seen small reservoirs filled 
with crude oil, mineral oil, and had been told that that oil had been standing for three 
months without any detrimental effect to the reservoirs. M. Coignet, as a matter of fact, at 
his instigation, has filled pipes to a certain height with mineral oil in order to find if they 
leaked. After several months it was found that the oil is there, and they do not seem to have 
leaked. From information from Baku and various other sources where they seem to be using 
large reservoirs for the storage of naphtha, they seemed all right; but still, if he were asked to 
take the responsibility of it, he did not think he would dare to do it, because there still seems 
to be a certain amount of doubt. 

Mr. Vawdrey asked at what age concrete was sufficiently indurated to resist the action of 
mineral oil. It appears it does not set after a certain age; at what age did the author consider 
the dangerous period is passed ? 

The President, with reference tc the question of waterproofing compounds, had found in 
all cases after three months the crushing strength is gradually reduced. He had only gone 
on now for a period of three years; but it is going down all the time. He was making some 
further experiments with waterproofing compounds guaranteed to increase the strength. But 
there is no doubt about it they may temporarily do good and stop leakage, but in time they 
weaken the concrete so seriously that damage is likely to take place. 

MR. LAURENCE GADDS REPLY. 
Mr. Oadd: Mr. Butler says many of the test results are anomalies, and he drew attention 
to the fact that in all cases an average of not more than three is given. This was due to 
fact that not sufficient time had been available for a larger number of test pieces. 

E 



THE CONCRETE INSTITUTE. [CONCRETE] 

It was not claimed for the paper that it was an exhaustive treatment of the subject ; but, 
looking at it generally, even the two or three briquettes can be accepted as some indication — 
if not by any means final — of a line of investigation which it is hoped will be carried out by 
other members of the Institute.. 

As to the immersion in tannic acid, it might certainly have been better to have immersed 
water-gauged briquettes in tannic acid. But, as a matter of fact, the particular tests described 
in the paper were not made for the purposes of this paper, but were made with another object 
altogether. It would have been impossible during the time available for the preparation of 
this paper to have given tests of more than a month or two's duration, so that some tests were 
used which had been made about eighteen months ago for a totally different purpose. 

Mr. Butler's point about greasing moulds is an excellent one. He also raised one or two 
other questions. He wanted to know how the oil and grease were mixed with the cement or 
with the concrete. The amount of oil was very small ; it was one-tenth of the weight of the 
actual dry cement, and was mixed with the dry cement in the first instance. With the harder 
fats, like lard, the lard was slightly warm and the whole was mixed in the mortar with the 
dry cement ; it was rubbed into the cement before gauging at all. Then the sand was added 
and the whole mixed up, and finally it was gauged in water in the usual way. 

As to the method of making percolation tests, slabs of concrete 3 in. thick and 10 in. 
square are taken, and these slabs are put between rubber washers (indiarubber an inch thick), 
and they are squeezed down between two steel plates, those steel plates forming the flange of 
a cup, more or less, in shape. The bteel plate joins on to the rubber. There is one india- 
rubber washer, then the slab and one indiarubber washer below, and the whole is screwed 
down so as to make it tight at the joints. At the top of this cup there is an inlet through which 
the water is forced. The water pressure is got by means of a pump and an accumulator, so as 
to keep constant pressure on the slab. The other cup is simply perforated at the bottom where 
the water is collected. 

Regarding Mr. Alban Scott's remarks about percolation of concrete, his experience had 
shown that after a time even concrete which was porous closed up. As the concrete goes on 
indurating, setting, hydrating, the pores gradually close up, and there is no better way of 
making a concrete waterproof than to force water through it for an hour or two under very 
high pressure. If it is then allowed to dry it becomes almost absolutely waterproof. 

Regarding Mr. Vawdrey's remarks as to what extent a diminution in the size of the block 
was observed, it was found that the edges were worn ; there were no sharp edges ; even those 
briquettes which stood a certain amount of strain on the outside were indeterminate in shape. 

Regarding the term "saponification," it comes from the fact of the decomposition of a 
neutral oil. In speaking of a neutral oil, it is to be quite understood that the ordinary oils as 
we know them are not fatty acids; they are compounds of the fatty acids, just in the same way 
as salt is a compound of hydrochloric acid. Tallow in combination with calcium hydrate 
largely consists of a dry stearine; it is a compound in wdiich a portion of the hydrogen of 
the fatty acid is replaced by glycerine radical, and the process of saponification is merely 
to dissociate the glycerine radical again from the fatty acid. The glycerine is set free, or 
rather the glycerine radical which combines with the element of water ; glycerine as we know 
it and the fatty acid which was formerly in combination with the glycerine radical goes into 
combination with the lime, with the calcium. The reason it is called saponification is because 
in these cases the metallic salts which are formed from these fatty acids are all soaps, hence 
the term "saponification," or the production of a soap. 

As to Mr. Workman's remarks about the waterproofing compounds which are being pushed 
pretty well on the market just now, the lecturer said he was not interested in waterproof 
compounds either one way or the other, but for his own information he had examined, 
analysed, and tested in relation to their effect upon tensile and crushing strength, and on 
waterproofing in particular, practically all the waterproofing compounds that are on the 
market. He would go so far as to say that they are practically all the same. 

The bulk of these compounds consists of hydrate of lime with about 10 per cent, of lime 
soap. The reason of this is it is supposed to be calcium stearate, but owing to the crude 
way in which the calcium stearate is made they only get about 10 per cent, of calcium stearate, 
and the rest is simply lime. It may be agreed that they may have some action in stopping up 
pores, so far as the free lime is concerned — thai is to say, the lime hydrate — but, as a matter 
<>l factj tin- labium stearate pari oJ il is a detriment rather than an assistance. The lecturer 
had not found a single one of these compounds which renders concrete more waterproof than 
plain concrete, but rather the i 



130 



fo, CONSTBUCTlONAlJ 
[Ci. ENGINEERING-*-? 



NEW GENERAL POST OFFICE, MILAN 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reliable information 'will be presented of nezu "works in course of 
construction or completed, and the examples selected "will be from all parts of the 'world. 
It is not the intention to describe these "works tn detail, but rather to indicate their existence 
and illustrate their primary features, at the most explaining the idea "which served as a basis 
for the design. — ED. 



THE NEW GENERAL POST OFFICE IN MILAN. 

Although only opened seven years ago, the General Post Office of Milan has been 
Found quite inadequate for its purpose, especially since the taking over of the tele- 
phone service, and a new building lias been constructed recently for the three depart- 
ments of Posts, Telegraphs, and Telephones. This building incorporates a pari of the 
former Post Office, and also covers the site of two churches and a number of offices 
and houses. 

The walls and the vertical skeleton of the new building, with the exception of the 
ground floor columns, are constructed in brickwork set in hydraulic lime, whilsl the 



% 




•assa. 2&K2HE 




Entrance to Telpprnne Offices. 
The New General Post Office, Milan, Italy. 



■31 



NEW WORKS IN CONCRETE. 



[CONCRETE] 




Process of Concreting a Floor. 
The New General Post Office, Milan, Italy. 




Underside of Roof, Urban Telephone Exchange during removal af centering 
Tin: New General Post Office, Milan, Italy. 



Ij2 



1 



CDN5TUUCTIC*-UI1 
EMCJNEEKINC-.^I 



NEW GENERAL POST OFFICE, MILAN. 




2 S 



z o 






'53 



NEW WORKS IN CONCRETE. [CONCRETE 

floors, beams, terraces, etc., and the ground fioor columns, are of reinforced concrete. 
The most important part of the building in this respect is the urban telephone 
exchange, a largo hall 105 metro long and 14 metres broad. The roof of this hall is 
a hollow floor, carried on arched beams, above which are the pilasters and architraves 
of the attic floor, also in reinforced concrete. The construction of this roof is seen in 
Fig. 3. In order to relieve the outer walls of thrust, two longitudinal girder- of 
reinforced concrete are used to take the thrust, these again transmitting a purely 
vertical load to the walls. 

The work was carried out rapidly, as much as 60 cubic metres of concrete bein^ 
put in place on a favourable day. Loading tests were carried out on each floor with 
one and a half times the prescribed load, the deflections observed amounting to only 
5^3 of the span, without permanent deformation. The reinforcement is mainly on the 
Volpi system. The contractors were Galimberti Bros., and the constructional 
engineer Sr. G. Ferrini. 

Our illustration- show (1) the entrance to the telephone offices; (2) the process 
of concreting a floor; (3) the underside of the roof of the urban telephone exchange 
during the removal of the centering ; and (4) the main entrance of the new building. 

In conclusion we would add that we obtained our particulars from an article in 
the Italian journal // Monitore Tecnico written by the engineer, Mons. Giovanni 
Pizzamiglio, of Milan, and we are indebted to the latter for our illustrations. 

BALLINGDON BRIDGE, SUFFOLK. 
The existing timber bridge over the River Stour between Ballingdon and Sudbury has 
rccentlv been demolished and a new bridge constructed in reinforced concrete on the 
Hennebique svstem, to give the increased accommodation necessary for carrying the 
growing traffic of the district. 

The new bridge is about 112 ft. span between the concrete abutments which have 
been reconstructed, and is supported on four rows of four reinforced piles abreast, 
making three spans of about 37 ft., the centre span being slightly larger than the end 
spans. The reinforced concrete piles are 16 in. by 16 in. in cross-section, the longest 
being 29 ft. and the shortest 17 ft. overall, and they were driven without any difficulty. 

The width of the new bridge between the curbs of the roadway is 26 ft. with a 
5 ft. footpath on either side, making a total width between parapets of 36 ft., the 
footpath being carried by cantilever brackets at intervals on the external main beams. 
The main beams of the bridge are all 10 in. wide, those in the centre bay being 
1 ft. 9 in. below the decking level and in the end bays 1 ft. 6 in., the reinforcement in 
the inner beams of the end bays consisting of six main tension bars iff in. diameter 
and two bars ij in. diameter in compression, the shear members being 13 in. by g in. 
hoop steel throughout; the outer main beams are arranged to project up to pick up 
the footpaths, making a total overall depth of 3 ft. 3 in. Caps are provided to each 
of the pile heads just above normal water level, and the horizontal bracings, 15 in. by 
S in., come immediately above them. The decking is 5-5 in. thick throughout, the 
main reinforcement consisting of h-\n. diameter bars straight and curved alternately 
at 6-in. centres at the bottom, with J-in. diameter bars straight at the top spaced 
every 9 in. The secondary beams are 12 in. deep, 6 in. wide, and are at 5-ft. centres, 
the reinforcement consisting of two bars 1 in. diameter with shear members out of 
ij-in. by yg-in. hoop steel. 

The parapet, which is in reinforced concrete throughout 4^ in. thick, is similar to 
that of Rod Bridge recently constructed in the district, and was cast in 5-ft. lengths 
and afterwards fixed in situ, the coping being moulded on same afterwards. 

In order to keep the road open to light traffic, it should be mentioned that tin- 
bridge was constructed in two halves, a portion of the old bridge being left up until 
one-half of the new structure was opened, when the old portion of the bridge was 
demolished and the new bridge completed, the roadway being finished off with 
" Tarmac " <m hardcore and the footpaths in granolithic. 

The work was commenced in April last and the new bridge was tested on 
December 3th with very satisfactory results, the maximum deflection observable under 
the full test load of three steam-rollers, each weighing 16 tons and travelling two 
abreast and one following, being slightly over one-sixteenth of an inch. 

The architect for the work was Mr. Ainsworth Hunt, the County Surveyor For 
Suffolk. The consulting engineers were Messrs. L. G. Mouchel and Partners, Ltd., 

•31 



fa, CONSTRUCTIONAL 
[h- ENGINEERING — , 



REINFORCED CONCRETE BRIDdE. 




NEW WORKS IN CONCRETE. 



[IDNCBETEJ 




136 



E 



constbultionai ; 

ENOrNEEKlNG — , 



REINFORCED CONCRETE WATER TOWER. 



of 38, Victoria Street, Westminster, S.W., who prepared the reinforced concrete 
detail drawings, and the contractors were Messrs. Holloway Brothers (London), Ltd., 
of ni--i Belvedere Road, Lambeth, S.E. 

REINFORCED CONCRETE WATER TOWER AT SCOPWICK. 

The Sleaford Rural District Council have again added to the large number of village 
water supplies, which they have provided during the past fifteen years, within the 
large area comprising their district. 




In course of construction. 
Reinforced Concrete Water Tower, Scopwick, Lincolnshire. 

A scheme for supplying the parishes of Scopwick and Kirkby Green, with 

probable extensions to the pretty village of Blankney and Blankney Hall, one of the 
country seats of Lord Londesborough, who has contributed one-half of the total cost 
of the works under notice, comprises a dee]) bore into the Lincolnshire Oolite, 
pumping-station and pipe tracks. 

With the exception of the wrought-iron access ladders, the water-tower ; 
structed entirely in reinforced concrete on the Hennebique system, even including the 
pole projecting some 14 ft. above the top of the cupola. 

The elevated reservoir consists of a cylindrical chamber, 24 ft. in diameter inside 
bj 11 ft. 3 in. high from floor level to the underside of roof, ami has a capa 
27,000 gallons. The outer shell of the reservoir is 5 in. thick, the b 



NEW WORKS IN CONCRETE. 

same thickness. The roof i> 4 in. thick, and i> provided with an ornamental oornioe 
about 2 ft. high, forming a parapet. 

At the centre of the reservoir is a reinforced concrete tube of 2 ft. 6 in. diameter 
inside, affording accommodation for the ladder furnishing means of access to the roof, 
the top of the opening being covered by a cupola 8 ft. high. 

The reservoir is supported at the height of 50 ft. above ground level by a tower of 
hexagonal form, consisting of six inclined columns braced laterally at five levels. 

The footings of the columns an- bedded on limestone rock occurring near the 





Complete Structure. 
Reinforced Concrete Water Tower, Scopwick, Lincolnshire. 

surface, and at the ground level they are connected by a moulded plinth. The inter- 
mediate bracings are utilised for the support of the ladders and the landings in con- 
nection therewith. 

At the upper end the columns are connected with the bottom framework of the 
reservoir, and are additionally braced by a series of arches. Cantilever brackets 
projecting from the columns provide for the support of the outer part of the cylindrical 
reservoir. 

The reinforced concrete work is monolithic throughout. It i- one of the very few 
reinforced concrete water-tower- erected under a loan granted by the Local Government 
Board. 

The interior fa^- of the reservoir i- rendered \ in. thick in two coats of cement 

'38 



1 



CONSTRUCTION A LI 
ENGINEERING — J 



CONCRETE BUILDLXCS. 



and Medusa waterproofing compound, and when under tesl the construction was found 
to be perfectly watertight. On the pole fixed al the top <>f the cupola is a spherical 
balance weight, which will act as a water-level indicator, being attached to a copper 
Boat inside tin- reservoir, thus showing to the engineer at the pumping station situate 
1,200 yds. lower down the valley of the Scopwick Beck the depth of tin- water in tank. 

The whole of the work was carried out under the personal supervision of Mr. 
\\ . B. Marsden, the engineer and surveyor to the Sleaford Rural District Council. 

The reinforcing steel was supplied by the Whitehead Iron and Steel Co., Ltd., of 
Tredegar; the aggregate for the concrete by the Groby Granite Co., Ltd. The pumping 
station and pipe tracks were constructed by .Messrs. \Y. Pattinson, Contractors, 
Ruskington ami London; the machinery for the station was supplied by Messrs. 1\. 
Hornsbv and Sons, Ltd., Grantham; and the water-tower was constructed by the 
Liverpool Ferro-Concrete Contracting Co., of Liverpool. 

ST. MARY'S PRESBYTERY, STOCKTON-ONTEES. 
This building was erected entirely of concrete stone and pitched-faced blockers and 
plain quoins, and consists of three floors, the ground floor having a large dining-room 




St. Mary's Presbytery, Stockton on-Tees. 

24 ft. by 14 ft., study, waiting-room, central hall, and a large kitchen with the usual 
offices ; the first floor has two studies, with bedrooms, bathroom, etc.; the second 
floor has four large bedrooms. 

The roof is covered with green Westmorland slates, and, with the buff-coloured 
concrete stone, forms a very pleasing effect. 

The total cost of the building was ,£"1,250, and it was erected to the order of the 
Rev. Father Taylorson, of Stockton-on-Tees. 

The school adjoining the presbytery was erected about five years ago, and was 
also built of concrete blocks, and a novel feature of this building is that the ;• 
is on the roof. 

PAGODA AT WYNYARD PARK. 

Tins pagoda was erected in Wynyard Park for the Right Honourable the Marquis 
Londonderry, and was constructed entirely of concrete stone, having 
with Corinthian capitals, cornice, etc., and in between the columns 

159 



NEW WORKS IN CONCRETE. 



[ CONCRETE) 



blocks, while the inside is panelled work with plain ashlar facings. The ceiling also 
is circular panelled, and is supported on concrete beams. The roof is marbled with 
white marbled chippings. 

The floor, doors, etc., are all made of oak grown on the Wynyard Estate. The 




whole of the stone for these two buildings was supplied by the Stockton Stone and 
Concrete Co., Ltd., of Norton, near Stockton-on-Tees, and the blockers, etc., were 
made by them with the Dring concrete block machine. 

Both structures were designed and erected under the supervision of the estate 
architect, Mr. Arthur Harrison, of Stockton-on-Tees. 



140 



1 



^ CONM'PUCTIONAl 
ENGINK.EK1NG— , 



NEW BOOKS. 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the leading books "which have appeared during the last feiv months. 



"Street Pavements and Paving Materials." 
By George W. Tlllson, C.E. 

London: Chapman & Hall, Ltd. New York: John 
Wilt-y & Sons. Pricel7s.net. 651pp. + xvii. 

In his preface the author states that an 
active participation in the construction of 
municipal public works, particularly of 
pavements, during' the past twenjty years 
has seemed to justify him in producing 
this book in order to show the evolution 
of the modern city street. 

With this in view he has given the 
reader in a concise form a history of road 
construction, and has presented in an 
interesting way the results of his own 
experience in the formation of roads. 

The historic portion of the book may 
be useful as a reference, but will not be 
much consulted by the engineer. Chapter 
IV., dealing with Brick-Clays and the 
.Manufacture of Paving Brick, will not 
interest the British engineer, who discon- 
tinued the use of paving bricks -some 
years ago as they were found to be un- 
suitable for the requirements in our 
cities. Too much space has been given 
to the composition of the various rocks 
and asphaltes, while the chapters on 
"Cement, Cement Mortar, and Concrete" 
and " Concrete Pavements " are most 
useful and contain a great deal of valu- 
able information. It is impossible, how- 
ever, in two chapters to do justice to these 
subjects — the author has really attempted 
too much; we think he might well, for 
example, have omitted the discussion on 
" The Effect of Salt Water on Cement 
Mortar," as one would never dream of 
using this in connection with concrete for 
road-making purposes. If " Harbour or 
Dock Construction " had been the title of 
the book a discussion of the subject would 
have been appropriate. The definitions of 
" lime " and " cement," a description of 
early cements, and the consumption of 
cement in the United States might have 
been omitted and the space saved devoted 
to a fuller description of the more prac- 
tical subjects, such as the " Effect of 
Frost on Mortar " and " Hand versus 
Machine-mixed Concrete." 

Mr. Tillson, in dealing with the im- 
portant subject of concrete pavements, 
describes the American practice in this 
respect; this description would have been 



much more interesting had he inserted a 
few cross-sections through concrete roads 
and an occasional photograph showing 

the various methods of construction; his 
Standard Specifications for (Vim nt are 
those adopted in 1909 by the American 
Society for Testing Materials, and are 
slightly different from the British Stan- 
dard Cement Specification. 

He quotes too much from trade circulars 
and specifications in dealing with concrete 
pavements, and does not go so fully into 
the merits of concrete as this material 
justifies, neither does he insert any illus- 
trations showing concrete roads in 
America. Surely those of New York 
City, Atchison (Kas.), Eldora (Iowa), 
Greenville (Illinois), California, and other 
places might have been referred to. 

However, the book is a useful contri- 
bution on an important subject. It contains 
much valuable information put in a crisp 
manner and to the point, and is a most 
desirable book of reference for every 
municipal engineer's office, and should be 
in the hands of every road-maker, be he 
contractor or engineer. 

There is much that one has not been 
able to review, there being such a wealth 
of material in the book that has to be 
passed by. However, the reader is bound 
to come to the conclusion that the use of 
concrete in road construction has un- 
doubtedly come to stay, and will become 
more and more general. 

"A Text'Booli on Roads and Pavements." 
By Prof. FrederloK P. Spalding. 

London: Chapman & Hall, Ltd. New York: John 
Wiley & Sons. Price 8/6 net. 408pp. 

The aim of the author of this book is 
twofold — to discuss the principles involved 
in highway work, and to outline the more 
important systems of construction. 

He is wise in omitting numerous 
statistics, which are not only uninterest- 
ing to the reader, but add to the cost of 
production of the book, and he has very 
fittingly devoted considerable space to 
methods of construction of coun'< 
which in these days when rapid 
are using all our roads, whether rural or 
town, make the construction of 
country road of as much import ir. 
that of the town. 



NEW BOOKS. 



rCQNCBETEl 



The book has been written so that it 
may be understood by those whose know- 
ledge of road construction is extremely 

limited, and it is easy to realise that the 
author is used to presenting knowledge in 
such a form that the engineering student 
may be able to follow him. 

While much that appears in the book 
is quite elementary to the road-maker— 
engineer or contractor — there is every- 
thing to indicate that the author under- 
stands his text. 

The book is in its fourth edition, and 
should be obtained by all interested in 
modern road construction. 

The chapter on Concrete Pavements 
deals with roads constructed of concrete. 
The author here deals with such important 
points as the mixing and laying of the 
concrete, its consistency, the thickness of 
concrete necessary, placing of expansion 
joints, the finishing of the road surface, 
the quality and strength of the Portland 
cement used, and many other important 
points. The chapter is weak, however, 
in that there is not a single illustration to 
assist the reader. What the author has 
to sav is put in a clear and readable form. 
Chapter I. on " Road Economics and 
Management " is an admirable one for 
the student, while that dealing with the 
" Drainage of Roads and Streets," and 
the chapters on " Road Construction," 
while they represent American practice, 
are different from our English methods. 

The chapter on " Bituminous Macadam 
Roads " is very interesting and instruc- 
tive. Brick pavements occupy a long 
chapter, but will not interest the British 
engineer. 

The book is an excellent one, written 

in a language which makes the subject 

perfectly clear, and by one who knows 

what he is talking about; the type is 

good, the few illustrations are clear, but 

in our opinion the book would have been 

more valuable had the author included 

many more illustrations, especially in 

those parts of the book which deal with 

modern types of construction, such as 

concrete pavements. 

" The Properties and Design of Reinforced 
Concrete — Instructions, Authorised 
Methods of Calculation, Experimental 
Results and Reports by the French 
Government Commission on Reinforced 
Concrete." Translated and Abridged by 
Nathaniel Martin, B.Sc, etc. 

London: Constable & Company. Ltd., 10 Orange 
Strict. Leicester Square, W.C. 119 pp. • xiv, price 
8/0 nets, 

Contents. — Instructions Relative to the 
Use of Reinforced Concrete Circu- 

1+2 



lar Issued by the French Ministry of 
Public Works — Draft Regulations 1>\ 
the Commission— The Experimental 

Work of the Commission — The Re- 
port and Draft Regulations of the 

Experimental Work — Some Conclu- 
sions of the Commission — Notes Pre- 
sented by M. Considere- Appendix. 
The French Commission was appointed 

by the Minister of Public Works in 
December, 1900, and it consisted of a body 

of engineers who had excellent experience 
in reinforced concrete work, and the re- 
ports are therefore of great interest and 
value, especially those dealing with the 
experimental work. 

The work extended over a period of six 
vears, and is of a very complete character, 
the object being to obtain results imme- 
diately applicable to practice rather than 
the solution of fine points in theory. The 
tests are particularly useful, as they in- 
clude the tests to destruction of several of 
the structures of the Paris Exhibition of 
1900, and there is very little evidence of 
experimental research in this country, 
although (theoretical matter i- becoming 
more or less plentiful. Several facts were 
established by the Commissi n as the re- 
sults of their experiments, some of the 
points considered being contraction during 
setting and hardening, elasticity, ductilitv, 
the value of spiral reinforcement, shear 
and torsion flexion ; and the designer 
of reinforced concrete should find the de- 
cisions put forward both interesting and 
instructive. 

The notes presented by M. Considere 
are extremely interesting, as they refer to 
the methods of making the tests and 
observations that were made during 
same with •explanatory and instructive 
remarks. 

The theoretical portion of the volume 
is also good, and the diagrams through- 
out are clear and well drawn. 

" Building Construction (Advanced and 
Honours Course)." By Chas. F. Mitchell, 
M.S.A., etc. 

London : B. T. Bateford, 94 High Holborn. 940 pp.+ 
viii, price 6'-. 

Contents.— Limes and Cements — Concrete 
— Asphalt - - Plastering - Stones — 
Bricks — Tiles, Terra-cotta ami Stone- 
ware-Iron ami Steel Timber — 
Paints and Varnishes (dass — Foun- 
dations — Brickwork -Flues, Fire- 
places and Tall Chimneys — Masonry 
Carpentry Half-timbered Work — 
Pillar-, Columns and Stanchions — 
Graphic Statics (dialers — Fire Re- 



CONS! UUCI IONaD 
,1M BERING — J 



[A ENG. 



A7ilV HOOKS. 



sisting Construction — Reinforced or 
Ferro-Concrete - Roofs and Roof 
Coverings — Joinery Stairs and 
Handrails— Sanitation, Water Supply 
— Hut Water Apparatus and Ventila- 
tion- Electric Bells and Lighting- 
Exercises Appendix and Examina- 
tion Papers. 
This is the seventh edition of what is 
probably the most popular book on build- 
ing construction in this country, forming 
as it docs the text-book in many technical 
schools where the subject is taught. It 
contains about eight hundred illustrations, 
and covers practically the whole subject 
of construction in a manner designed to 
meet the requirements of students. 
Although an excellent book, we feel that 
there are some points which should be 
drawn to the notice of the author, as, for 
example, the diagram shown in the illus- 
tration No. 134, page 278, where the con- 
crete under an 18-in. wall is only figured 
3 ft. wide. This should be the width of the 
footings, and the concrete should be 4 ft. 
Such an error is calculated to cause the 
unwary student some trouble if the dia- 
gram should be drawn as shown, com- 
mencing with the concrete and working 
upwards, when the wall will work out to 
in. thick only. The method of finding 
the depth of concrete under walls described 
on page 260 and illustrated on page 261 is 
not good, as it gives an excess not re- 
quired. A better method is to let the 
line at 45 from the top of the footings 
intersect a vertical line drawn from the 
opposite extreme projection of the foot- 
ings. This method will give results more 
in accordance with those obtained by 
calculation. The grillage foundation illus- 
trated on page 267 is obsolete, and no 
distance pieces, stiffeners or bolts are 
shown or mentioned. The chapter on fire- 
resisting construction might with great 
advantage be revised and amplified to 
bring same more in accordance with 
modern methods, especially in view of the 



great importance of this class of work. 
The concrete and steel floor illustrated 

in Fig. 305, page 581, is quite unsatis- 
factory, the illling in joists being in; 
quate for the span mentioned and the con- 
crete not being thick enough. The floor 
illustrated in Fig. 396 consists of steel 
troughs carried by plate girders, and the 
author suggests that the space under the 
troughs can be utilised for pipes or even 
ventilating purposes, but evidently over- 
looks the fact that to do this tin- webs of 
the plate girders would have to be cut 
away in such manner as to seriously 
weaken them. The chapter devoted to 
reinforced concrete has rightly been ex- 
tended, and should be sufficient to give the 
student an idea of the use and value of 
this material. We are sorry to see, how- 
ever, that the portion devoted to concrete 
is not more complete. Machine mixing 
is simply mentioned as an alternative to 
hand mixing, but no description is given, 
and no diagram or illustration of any of 
the well-known mixers appears, and this 
must be considered as a serious omission, 
as they are used on practically all impor- 
tant work. The portions devoted to 
graphic statics and calculations for pillars 
and girders occupy a considerable space in 
the volume, but they are very vague in 
many instances, and we doubt the ability 
of many students to follow the author or 
profit by the study of these chapters suffi- 
ciently to justify the large amount of time 
it would involve. If the author and his 
assistants would devote their attention to 
perfecting the work to comply with 
modern practice and delete many of the 
diagrams and much of the text which deal 
with more or less obsolete methods, there 
is no doubt that the effect would be the 
production of am almost perfect volume 
dealing with the very large subject of 
building construction. These remarks 
are merely given as the outcome of an 
honest criticism and a desire to assist the 
author. 






INDUSTRIAL NOTES. [CONCRETE^ 

INDUSTRIAL NOTES. 

These pages have been reserved for the presentation of articles and notes on proprietary) 
materials or systems of construction put forward by firms interested in their application. With 
ine advent of methods of construction requiring considerable skill in design and supervision, 
many firms noivadays command the services of specialists "whose vieivs merit most careful 
attention. In these columns such vieivs "will often be presented in favour of different 
specialities. They must be read as ex parte statements— "with ivhich this journal is in no -way 
associated, either for or against— but ive ivould commend them to our readers as arguments by 
varties mho are as a rule thoroughly conversant ivith the particular industry luiih ivhich ihey 
are associated. —ED. 



SEPARATORS. 

(System Von Grueber.) 
Whenever it becomes necessary for users of crushing and grinding machinery to con- 
sider new installations or additions to existing arrangements, the question of an 
efficient method of separation is one of several problems requiring careful consideration. 

First, the system must be decided. Screen-type or air (pneumatic) ; secondly, 
which of the two types of design will best suit the particular material and circum- 
stances of the user. 

As most practical people know from experience one type or design of separator 
will be the greatest success on one particular material ; whereas, on the other hand, 
it will turn out an utter failure on a different class of product. The present article 
deals with the separators of Messrs. C. von Grueber, 31-33 High Holborn, London, 
W.C., who are extensive manufacturers of the Screen and Air type separators (under 
several accepted designs). 

The Screen Type of Separator. — This firm can offer a separator designed to 
have screens supported or carried by springs or rods, and to which motion is imparted 
by tappets, cams, cranks or eccentrics. Certain materials require a combined sliding 
and shaking action, cxthers merely a tapping motion ; while there are materials upon 
which it is necessary to operate by a rocking screen sometimes combined with tappets. 

A feeding screw arranged within a specially designed case is always employed for 
equally distributing the material along the full width of the screen, and a simple device 
is utilised for regulating the flow along and down the screen. 

The screens are carried in a strong steel casing, provided with inspection doors 
for the feed screw and the screen meshing, while the whole front and back of the 
casing may be opened on hinges whenever it is necessary to remove the screen for 
cleaning purposes or to renew the meshing, the situation of the separator deciding 
whether it is more convenient to use the front or back opening. 

Any number of screens may be fixed in the casing according to the various samples 
desired, but usuallv the separator is provided with a guard screen in addition to the 
finishing screen. This arrangement relieves the finer screen from contact with a great 
proportion of the bulk passing through the machine which has no possible chance of 
passing through the meshing of the bottom screen. 

Of course, a certain amount of the 5-in. and less product must be allowed to pass 
the guard screen to the finishing screen, for the purpose of " scouring " the finer 
meshing— that is, to keep the holes of the meshing free and unobstructed ; but the 
additional effect is obtained of assisting the fine product through the fine meshing, 
thereby reducing to a minimum the possibility of any finished product passing out with 
the tailings <>r residue. 

We think one, if not the leading feature, of the separator here under review is the 
fad that the body or casing of the machine need never be altered in position once it is 
fixed, because the angularity, and consequently the fineness of the finished product, 
may be instantly determined by fixing the position of the finishing screen from the 
outside of the casing. 

To practical minds such an arrangement will be self-evident, inasmuch as it does 
away with the necessity of breaking the connection of the chutes leading to and from 
the separator casing, which it is impossible to obviate if the casing must he moved up 

and down supporting legs to change the fineness of the finished product. 
144- 



i 



CON.STk'lKTIONAlJ Cpp 4 r> a rp n D Q 

ENGINtKKINC. — _ "^ L>trt\ K A 1 U A O . 



It is claimed that the screen separator is a great advance upon the revolving, flat, 
or ordinary shaking sieve or dressing machine, because with the former type a very 
coarse meshing is only necessary to obtain a relatively fine product; for instance, 
suppose a finished sample is required, 80 per cent, of which must pass the too by 106 
test sieve (10,000 holes per sq. in.), then it is only necessary to use meshing having 
about 34 by 34 holes per sq. in. 

Again, by using coarse meshing the wire from which it is woven is proportion atelj 
increased in diameter and strength, thereby ensuring increased life and less cosl for 
the upkeep of the meshing. 

The coarse meshing also ensures an increased output of finished product, from 
the fact that the difficult}- of the clogging of the mesh is largely removed. 

The residue makes exit from the bottom edge of the machine through an opening 
(Mending the full width of the screen and usually delivering to a store-bin over the 
grinding mill; while the finished product gravitates down the bottom of the casing to 
an opening under which is fixed a conveyor for transporting the fine material to any 
desired point of delivery. 

Usually the conveyor is a main line of transit to the stores or silos, but in special 
cases a short conveyor is combined with the separator and is driven from the shaft of 
the feeding screw. 

A pulley at the opposite end of the feed screw drives the machine and all the 
operating gear and mechanism. 

The screen separators are made in several sizes to correspond with a given output 
or capacity, and the horse-power required is 5 for the smallest machine up to 3 h.p. 
for the largest size. 

In many cases — particularly where an exceedingly fine and " floury " product is 
required — it is impossible to use the " Screen " type of separator, and under these 
circumstances the " Air " or pneumatic type of separator must be requisitioned. 

"Air" or Pneumatic Separators. — These machines are made in sizes ranging 
from 3 ft. 6 in. to 10 ft. diameter, and requiring from g to 6 h.p. for driving purposes 
according to size. 

In conclusion, we may be allowed to point out that Messrs. C. von Grueber are 
sole manufacturers in Europe of the well-known " Maxecon " ring and roll grinding 
mill; and, in addition, the firm also make and supply all types of crushers, elevators, 
conveyors, automatic feeders, dust collectors, rotarv screens, etc. 

They also undertake to act as engineers for the re-construction of existing or the 
supply of new sulphuric acid plants, designed upon the latest and up-to-date Con- 
tinental systems. 

The Maxecon mills, intended for use in Great Britain and Ireland and the 
Colonies, are manufactured in England from the best English materials. 



i+5 



MEMORANDA. 



Iidno&m 




Memoranda and Ne-ws Items are presented under this heading, -with occasional editorial 
comment. Authentic neivs -will be -welcome.— ED. 



Repairing Si. Paul's. — The work of repairing the cracks in St. Paul's Cathedral 
has been commenced. The method employed will be cement grouting. A thin liquid 
of cement is forced into the cracks by means of a special machine, worked by com- 
pressed air and so forming a solid weld between the two sides of the crack. This 
process proved very successful in the repairing of Winchester Cathedral. 

Reinforced Concrete in the Protection against Hostile Aircraft at the New 
Naval Magazines, Portsmouth — The new naval magazines for the storage of high 
explosives at Portsmouth are being most effectively protected against hostile aircraft. 
Thev are situated at Bedenham and consist of a number of sunken reinforced concrete 
chambers completely covered so as to keep their identity hidden from above. 

A reinforced concrete pier is also being built for the use of small craft only, and 
a network of rails will enable the explosives to be conveyed direct to the magazines. 

Purification of Water Supply, Aberdeen.— -In connection with the purification 
of the city's water supply the Water Committee recently decided that the reservoir of 
Mannofieid and Cattofield be covered with reinforced concrete. 

Improvements at Havre, France. — In connection with the harbour improvements 
at Havre it is reported in 7' /? t* Times Engineering Supplement, that the existing 
southern jetty is to be greatly extended. This extension is to be in two parts, one 
comprises a section of 1,445 m. long constituted by a number of reinforced concrete 
caissons measuring 25 m. in length, 6 m. in width, and 5*75 m. in height, and the 
other 1,700 m. long formed with similar caissons in length and width, but 6 m. high. 

Reinforced Concrete for Coal Tips. — In order to meet the growing demand for 
coal shipment and to avoid the necessity for dock extension at present, the Barry 
Railway Co. have decided to erect five new coal tips on the south-western side of No. 1 
dock. The supports to these tips are to be in reinforced concrete. In the older tips 
wooden supports were used, but it has been considered that, owing to the reduced cost 
in maintenance, reinforced concrete would prove more suitable. 

Merrion Pier Scheme, Pembrokeshire.— After careful consideration and dis- 
cussion, and upon the advice of their engineer, the Committee appointed for the 
Merrion Pier and Baths scheme recommended the Pembroke Urban District Council 
that it would be desirable to have the entire pier constructed from end to end in 
reinforced concrete, and, subject to the sanction of the Local Government Board, it 
was recommended that the tender for this work be accepted, as also the tender for 
substituting reinforced concrete for repairs to the existing pier. 

A Proposed Scheme for Working-class Housing.— In a paper read by Mr. B. 
Wyand at the joint meeting of Western and South-Western Districts of the Institution 
of Municipal Engineers at Exeter some time ago, Mr. Wyand gave some particulars 
of a scheme lor working-class dwellings which is under consideration. The proposed 
building is to be 1 rect< d in Mile End on a site of 4^ acres, and is to have accommoda- 
tion for 5,550 tenants. The building will be of fire-resisting construction throughout, 
with fire appliances on every floor of every block, and reinforced concrete will In- used 
very largely in the construction. 

146 



:^SE£BS£y MEMORANDA. 



Tables of Reinforced Concrete. -It is reported in the Tonindustrie Zeitung that 
a manufacturing firm had recently made an experiment in using reinforced concrete 
workshop tables in place of cast iron ones. These babies have proved more economical 

to make, and they can be made very much quicker than the iron ones. 

The latter cost about 420 marks to make, and delivery could only be made at 
between three and lour weeks when single orders were placed. On the other hand, 
il e reinforced concrete tables can be made at a cost of about 180 marks, and three 
tables can be turned out in a week ready for use. 

The top of the table is reinforced with an angle iron framework, and the ten legs, 
which each table lias, are also reinforced and joined to the table top by T-irons. The 
tensile stress is taken up by six 16 mm. round iron bars which are joined to the 
framework. In order to protect the edges of the table a narrow angle iron, 30 mm. 
by 45 mm., has been put round same. 

The cement mixture consists of Portland cement and unsifted, but not too coarse, 
gravel in the proportions of 1 : 4, and the top surface of the table consists of one of 
Portland cement and two of sand. 

Before setting, granite and fine basalt are beaten into the top, which is then 
covered with neat cement. After proper hardening the table top is smoothly and 
evenly rubbed down. 

The tables stood a test weight of 5 tons without being damaged in any way, and 
even heavier pieces of work did not harm them. 

The Society of Engineers" Status Prize. — The Council of the Society of 
Engineers (Incorporated) may award in 1913 a premium of books or instruments to 
the value of £10 10s., for an approved essay on " A scheme for the registration of 
Engineers, including particulars concerning the registration of Engineers in British 
Colonies and foreign countries." The Council reserve the right to withhold the premium 
if the essays received are not of a sufficient standard of merit. The competition is open 
to all, but, before entering, application for detailed particulars should be made to the 
Secretary, 17, Victoria Street, Westminster. The last date for receiving essays is 
May 31st, 1913. 

Concrete Rockwork at the Zoological Gardens. — The improvements at the 
Zoological Gardens, which are the outcome of a gift to the Zoological Society by 
Mr. J. Xewton Mappin, head of the firm of Messrs. Mappin and Webb, are to comprise 
a number of terraces and rockwork, which latter is to be constructed of steel and 
cencre'e, and we hope in a future issue to give some further details of this work. 

Large Reinforced Concrete Cotton Warehouses in U.S.A. — The Galveston 
Cotton Compress and Warehouse Co. are about to erect a reinforced concrete cotton 
press and warehouses to cover an area of nine acres at a cost of approximatelv 
£82,000. Some of the work is to be completed by July 1st next. 

Locomotive Coating Station. — A locomotive coaling station of reinforced concrete 
of 2,000 tons capacity, spanning seven tracks, has recently been completed at the 
Green Street yard of I he Philadelphia and Reading Railway, at Philadelphia, in 
connection with track elevation work in and about the city. 

The building is supported on seven rows of five columns each, and one end walk 
transversely, the rows of columns being placed parallel to outer lines of tracks. The 
floor of the pockets is of sufficient height above the top of rail to permit the largest 
engines to take on coal and dump ashes. The framework of the building is of 
structural steel and the walls, partitions, and floors of coal pockets are of reinforced 
concrete. The building is divided into twelve pockets equipped with two coal chutes 
each, and machinery for handling 100 tons of coal per hour. The ash handling 
machinery has a capacity of 250 yds. per ten-hour day. 

Coal is dumped from cars into a hopper located below the track at trie west end of 
the building, from which it is elevated and distributed to the pockets by machinery 
installed by the Link Belt Co., the contractor for the station. — Railway Engineering. 

San Francisco Station. — H.M. Consul-General at San Francisco reports to the 
Board of Trade that, according to the local Press, the Southern Pacific Railway Co. 
; ropose to spend nearly 1,000,000 dols. (about .£205,500) on a new terminal station at 
San Franoisco. The new station will be two storeys high and built of reinb 
concrete with a tiled roof. — Contract Journal. 

F2 147 



MEMORANDA. [CJQNCREXE 



Producing Polished Effects on Concrete Work. — Concrete slabs and brick are 
now being produced that are as fine in grain and structure as high-grade porcelain, 
showing an equally fine polish. The secret of the process consists in grinding the 
aggregates to as fine a powder as the cement. The mixture, one cement to as high 
'is twelve of aggregate, is then dampened just sufficient to pack well when pressed in 
the hand. It is then subjected to high pressure in strong iron molds, up to 5,000 
lb. per sq. in. The best results are obtained in slabs or plates slightly under 1 in. 
thick. The pressure is applied in four or more strokes. After each stroke the 
pressure plate is removed to permit the air to escape. After each stroke the pressure 
is increased. The object of grinding the aggregates to the same fineness as the 
cement is to prevent forming an arch in the stone, which always takes place where 
high pressure and coarse aggregates are employed. Then, again, if the pressure 
applied to the concrete exceeds the crushing strength of the aggregates, the aggregates 
will grind at the contact point in the mass, leaving powdered contact points which 
weaken the concrete. This defect is entirely overcome by using a fine powdered 
aggregate. It will be seen that high pressure and coarse aggregates are inconsistent 
for fine work. Coarse aggregates can, however, be used where the mould produces 
forms in the shape of an arch, and the pressure applied is below the crushing strength 
of the aggregates. It is extremely bad practice to use high pressure in moulding 
concrete blocks over 4 in. high, on account of the danger of the arching of the 
aggregates. Tamping square or hollow concrete blocks is always to be preferred for 
sound work. — Cement. 

Specification for Cement-top Floors. — The Aberthaw Construction Co., Boston, 
specify as follows for cement-top floors. This specification is for laying hard fini>h 
on new rough concrete, either paling or slabs supported by forms. 

Finish to be mixed one part of cement to two parts crushed trap rock or hard 
gravel screening, which will pass through a J-in. sieve, and from which the fine dust 
has been removed. This is to be thoroughly mixed in a mixing box or by a machine 
mixer, with an amount of water to produce a plastic but not a sloppy consistency ; 
spread on the under-concrete before either the finish or the under-concrete has had 
time to set, floated with a wooden float to a true level and then lightly trowelled with 
a steel trowel as soon as possible to bring it to proper level and to smooth the top 
slightly. This will give a finish which is pebbly. It will not be dead smooth or slick 
like a sand finish. 

After the finish has been trowelled and has set sufficiently so that the covering 
will not mar the surface, it should be covered with sawdust, sand, cloths, or any 
other material which will hold water on it continuously. In building reinforced 
concrete work, difficulty will be caused by the sand and sawdust blowing about the 
work, filling the forms, and generally getting in the way. In working around a 
textile mill there is usually plenty of old bagging, and in a paper mill there are usually 
plenty of old felts which can be borrowed for the purpose of preventing this. 

The finish should be kept soaking wet for at least a week or better for ten days. 
After two davs it is possible to put up studs and do miscellaneous work on the top of 
the new finish, provided it is not allowed to dry out. 

Concrete in Mine Air-ways. — The use of concrete in mining may be extended to 
replace timber in airways. The roof of most coal mines is formed of shale, which 
deteriorates rapidly where exposed to the weather, thus necessitating a large amount 
i f timbering in entries. If this weathering could be overcome, little timbering would 
be necessary. This has been done by the Bethune Co., of the Pas-de-Calais district , 
of France, by lining their gangways with reinforced concrete made of burned shale, 
boiler ash, cement and water. This mixture requires fifteen days to set. The rein- 
forcement consists of 4-in. arched rods, placed 32 in. apart, and further strengthened 
by round 2-in. rods, placed lengthwise, q in. apart. Not only does this method reduce 
the cost of timbering, hut it prevents interruption in hoisting, due to falls of roof; 
watering can be easily and thoroughly done; lighting is good, as the walls are light 
coloured, and danger clue to falling roof when timbering is destroyed by a runaway 
trip is absent. —The Concrete Age. 

Temperature Changes in Concrete when Setting. — A paper read by W. D. 
Maxwell before the Iowa Engineering Society sets forth some interesting and 



I 



gSTSSKS 1 -] MEMORANDA. 



important data on the temperature of ooncrete during setting. Tests were made 
during work on Des Moines river concrete bridge. The observations were made in 
various parts of piers and abutments composed of 1:3:6 ooncrete, with thermometers 
placed in pipes sel in concrete. The points whore readings were taken were, from 
3 to 10 ft. from surface and face of concrete. The temperatures recorded show an 
increase of 15 decrees to 20 degrees Fabr. above temperature at time of pouring, in 
the concrete mass during setting, the maximum being reached in seven to ten days 
after pouring. Then the temperature falls, the rate depending on outside temperature. 
This risk in temperature was shown to he substantially the same, regardless of outside 
temperature, some of the tests being made in freezing weather and others during 
summer. — The Concrete Age. 

Disadvantages of a Hardwood Floor over Concrete. — In speaking of the 
disadvantages of a hardwood floor over concrete, Leonard C. Wason, president of the 
Aberthaw Construction Co., Boston, remarked that besides the cost there is the added 
dead-weight of the screeds, cinder fill, under floor, and upper floor. Dead-weight adds 
to the cost of the supporting construction of the foundations and adds other cost 
besides that of the floor itself. 

Tar and Cement Pavements in Germany. — Experiments have been made in 
Bremen and elsewhere with a street pavement composed principally of tar and cement, 
and which is called " terbacca." 

A test section at the Oldenburg freight station shows, after two years of heavy 
traffic, but little surface wear and no cracks, although laid on filled ground. 

The tar-cement pavement is laid on a bed of 5 in.to6 in. of concrete, or over broken 
stones slicked with cement mortar, say about 2 in. or 3 in. for ordinary streets, f in. 
to 1^ in. for foot pavements, and ij in. to 2 in. for courts. The mixture is made up 
of ninety volumes of hard, broken stone of three different sizes, ten of gravel and sand, 
and forty to sixty of Portland cement, mixed dry, then 10 per cent, of water is added, 
and at least five parts of coal tar, thinned down with a solvent. The tar-cement 
mixture is laid on much more quickly than required finally, and tamped down with 
a 6-lb. rammer to the required thickness. Where grades are unusually steep more 
cement is used than on levels. 

To prevent the formation of cracks, it is sufficient in ordinary climates to leave 
openings of f in. every 40 ft., filling these with asphalt. 

In Gothenburg, Sweden, and on the Kaiserstrasse in Hagen, Wesphalia, this 
pavement has done well; and in the latter city the tar-cement covering is only 7 cm. 
(1*78 in.) thick, but a week after its laying it is run over by a steam roller without 
showing any signs of ill-usage. Here the grade is r6o. 

In the matter of impermeability, after subjecting plates 1 cm. to 2 cm. (C394 in. 
to 0788 in.) thick to water columns in glass pipes 2 m. to 2\ m. (5*56 ft. to 8*2 ft.) 
long for six weeks, the under sides of the plates were not wet. — The Contract Record. 
A Concrete Scow. — A reinforced concrete scow for towing purposes on the lake 
has been built in Michigan City, Ind., says the Concrete Age. The craft will have a 
carrying capacity of 25 tons, and will be 14 ft. by 40 ft. by 3 ft. 6 in. The walls will 
be 3 in. and strongly reinforced. Only the deck plankings and fenders will be of wood. 
The life of a concrete scow will be much longer than that of a wooden one, and the 
concrete will stand a greater shock than a 6-in. timber. 

Concrete Floors for Foundries. — A number of experiments have recently been 
made which show that if iron borings are used in place of a portion of the gravel 
mixed in concrete, floors of this material can be successfully used in certain portions 
of foundries. Many foundrymen are interested in the use of concrete floors, but have 
generally found them unsatisfactory because molten iron will not lie on concrete on 
account of its porous, and, therefore, generally moist condition. The mixture recom- 
mended consists of one part cement, three parts sand, four parts gravel, and one 
part of iron borings. It is stated that floors made from this mixture are perfectly s 

A Reinforced Concrete Office and Factory Building. — An interesting example 
of the adaptability of reinforced concrete, for an office and factory building, is that 
afforded by the recently erected structure of the Gillette Safety Razor Co. of Canada, 
Ltd., Montreal, P.O. 

The structure contains about 50,000 sq. ft. of floor surface, its outline being 

149 




/^/^CVT/^TYrrnri? BTCONSTRUCTIONAI^i 



"Simplex" Steel Sheet Piling 



(Patent) 



1 # l> 

22 lbs, per super foot when interlocked 

Rolled Sections 8 ins. wide, of symmetrical shape 
and strong interlock. Narrow units for easy 
handling. Watertight owing to large interlock. 

CAN BE DRIVEN WITH HAND MAUL. 

Stocked in following lengths for dispatch at few hours' notice : — 
6, 8, 10, 12, 14, 16, 18, 20, 24, 28, 32 feet. 



On hire only for United Kingdom unless for 
permanent work. 

SOLD OUTRIGHT FOR ABROAD. 

Note— FOR HEAVY WORK OUR UNIVERSAL JOIST 
PILING SHOULD BE USED. 

All particulars from 

THE BRITISH STEEL PILING C? 

Dock House, Billiter Street 

London, E.G. 

Telephone 
1414 Avenue Telegrams 

1414 Central " Gramercy, London" 



Please mention this Journal "when 'writing. 



[f T CONSTBOlTlONAi; 
£ v fc.NGlNEF.RlNG — , 



MEMORANDA. 



irregular. The longer sides are i:: ft. and [05 ft., while bhe building is five si 
high with basement. 

The suitability of reinforced concrete to architectural treatment is here well 
illustrated. On all exterior concrete above the bell course, a smooth surface was 
obtained by rubbing with carborundum blocks, while below ibis point the concrete 

was bush-bamniered. 

The flat slab or girderless floor system of construction was used in this building, 
thereby eliminating beams, which tend to cut down the headroom, obstruct the light, 
and gather dust and prevent the satisfactory operation of automatic sprinklers, with 
which this building is entirely equipped. The column spacing is 20 ft. by 16 ft. 10 in. 

The reinforced concrete floor slab for the first floor is <)J, in., but the other floors 
are 85 in. thick. The finished floor in each case is a i-in. maple top on 3 in. by 4 in. 
screeds, 16 in. on centres, embedded in 3 in. of cinder fill. The height of stories is 
ti ft. 6 in. from floor to floor. 

This building was designed by Lockwood Greene and Co., Boston, Mass., and 
the general contractors were the Atlas Construction Co., of Montreal. 

Recent Reinforced Concrete Works in Alexandria. — Our attention has been 
called to the fact that the reinforced concrete pontoons illustrated in the above article 
; n our January issue, pp. 25 and 26, were according to Hennebique designs. 

Reinforced Concrete Fence Posts. — In further reference to the remarks in our 
January issue regarding the use of concrete at the Doneaster Agricultural Show, we 
give herewith an illustration of some fence posts erected at that exhibition by the 
Reinforced Concrete Fence Posts Co., Ltd. This company is now erecting fences or 
supplying the materials for their erection to seven of the principal railways of England, 
Metropolitan Water Board, Port of London Authority, and many private estates. 
There is often a great deal of prejudice to overcome in the introduction of a new 



AjL 






REINFORCED CONCRETE FENCE 



v i r 

. \ 1 i 



1111. 






Reinforced Concrete Fence Posts at the Doncaster Agriccltural Show, 



material, but the advantages of these posts as compared with wooden ones have been 
dealt with by us in former issues, and their almost universal adoption set ms to b 
only a matter of time. Reinforced concrete will neither rot nor burn ; in fact, tin 

posts are benefited by wet or sodden ground, as the moisture assists in th 
action which takes place in the hardening of the Portland cement. Cement with 
adequate reinforcement and specially graded aggregates, all carefully manipulated, 
insures a monolithic casting of the greatest strength. The company are also manu- 
facturers of railway gradient posts, mile posts, and concrete lettering, etc. 



I?I 



MEMORANDA. [CONCRETE) 

TRADE NOTICES. 
River Trent Protection Works— Reinforced Concrete Construction. The City 

Corporation of Nottingham has accepted the tender of Messrs. Gibbons and Turner, 
of Nottingham (licensed contractors for the " Piketty " system of reinforced concrete), 
for the execution of the above, in accordance with the plans of Mr. Arthur Brown, 
M.I.C.E., City Engineer. 

The whole of the work is to be carried out on the " Piketty " system of reinforced 
concrete construction, which has been selected in competition. Full particulars of 
this method can be obtained from Messrs. Piketty, 14-18 Bloomsbury Street, W.C. 

ENQUIRIES. 

I would be much obliged if you would kindly advise me through your valuable 
paper as to how to remedy and repair concrete girders, beams, and columns which 
have been cracked bv electrolytic corrosion, just as per the very interesting article and 
photos by Mr. Cecil H. Desch, D.Sc, Ph.D., in your journal of November, 1911, 
Vol. 6, No. 11. (Signed) Anglo-Indian. 

To the Editor, Concrete and Constructional Engineering. 

Reply. 
All damaged concrete should be cut out, exposing the reinforcing rods, which 
should then be scraped clean. It is assumed that the damage has not gone so far as 
to eat away the metal to any appreciable depth. In making good the concrete, a 
rich cement mixture should be used, the aggregate being broken small enough to pass 
a f-in. mesh and mixed with sand in the best proportions to give a dense concrete. 
The denser the concrete the better. Of course, the usual precautions must be taken 
in joining the new with the old work. 



BRITISH IMPROVED CONSTRUCTION CO. 

Telephone: 4067 Victoria. LTD. Telegrams; " Btconcrete, Vic. London. " 

" B I C " 

47 VICTORIA STREET, WESTMINSTER, S.W. 

Manufacturers of all kinds of 

Concrete Constructional Materials 

(Plain or Reinforced) 

Including PIPES, PARTITION AND PAVING 
SLABS, SLEEPERS, STANDARDS & POWER 
TRANSMISSION POLES, HOLLOW BEAMS 
AND FLOORS, FENCING POSTS, etc, etc., 
by the well-known "JAGGER" PROCESS. 

Engineers and Contractors Own designs carried out to order 

SPECIALITY. — Reinforced Concrete Pipes for High Pressures, abso- 
lutely Impermeable. Our Concrete weighs 156 lbs. per cubic foot. 



Please mention this Journal tvhen •writing. 




- < 

3 £ 



CONCRETE, 

AND 

CONSTRUCTIONAL ENGINEERING 



Volume VIII. No. 3. London, March, 1913. 

EDITORIAL NOTES. 



CONCRETE ROADS. 

Although concrete is gaining a firmer foothold in this country and its use- 
is becoming- more general for all manner of buildings, it seems extraordinary 
that, comparatively speaking, so little study has up to the present been given 
to the question of its employment on our roads. 

The use of heavy motor traffic is on the increase and is causing consider- 
able anxiety to those who have charge of the maintenance and building of our 
roads and highways; and although many experiments have been made to 
discover the most suitable material from the point of view of economy in con- 
struction and maintenance, a final solution has so far not yet been arrived at. 

In our present issue we publish an article by Mr. E. R. Matthews, Borough 
Surveyor of Bridh'ngton, on " Concrete Roads and Footways," which goes to 
bear out in some measure the experience acquired in the United States. In 
America concrete is being employed on a large and extensive scale for high- 
ways, and most of the literature seems to go to prove that the material has many 
advantages, viz., to enumerate one or two only : the construction is not difficult, 
the roads cost little to maintain, and they are smooth. On the other hand, 
like everything else, there are some disadvantages attaching to its use, but 
these, w r e hold, are far outweighed by the accruing gain, and, what is more, 
as has been proved in American practice, these difficulties can be overcome. 

One of the disadvantages mentioned by Mr. Matthews — namely, that these 
roads are inclined to be slippery — does not seem to be borne out by many motor 
users in America whom we have consulted, for, evidently in order to avoid this 
trouble, American engineers have recently adopted the practice of rendering 
the surface slightly gritty. Further, the tendency to crack, which is one of the 
alleged disadvantages, is apparently also one that can be easily remedied. 

We propose publishing some American experiences in our subsequent 
issues, and would recommend that our county and borough surveyors and our 
municipal engineers should accord this question of concrete roads greater 
attention. 

In conclusion, we venture to express the hope that at the Road Congress to 
be held this summer the subject will be given some prominence, and that the 
problem of special motor roads on the main routes of communication may be 
discussed. 

ROAD BRIDGES OF REINFORCED CONCRETE. 

At the present time, when so many of our provincial corporations and 
county councils are considering the question of reconstructing old bridges or 
building new ones, a few words on this subject may not come amiss. 

We have read with considerable interest in the daily Press the accounts of 
the proceedings of the various corporations when debating the advisability or 
non-advisability of erecting or reconstructing bridges in reinforced concrete. 

b 2 153 



REINFORCED CONCRETE ROAD BRIDGES. [TONCREXEJ 

A case in point is the cross-river communication at Newport, Monmouth- 
shire. The question of a new bridge or the reconstruction of the old one 
has for some time past occupied the attention of the Newport Corporation, 
and we observe that members of the Town Council seem very apprehensive of 
replacing the present masonry bridge by one in reinforced concrete, or even 
building a new one in that material. From quite recent information before us 
we note the recommendation of a resolution to rescind a former resolution to 
erect a bridge in reinforced concrete and that the sub-committee be empowered 
to confer with an expert with a view to adopting plans for constructing a stone 
bridge, and this, we believe, after matters had so far progressed that plans for 
a reinforced concrete structure had been drawn out. 

Similarly, in Norfolk, where quite a number of bridges of concrete are 
alreadv under construction or completed, it would appear that some of the 
members of the County Council are doubtful as to the ultimate success of the 
venture, and a short time ago a hope was expressed by some that nothing larger 
than the Coltishall Bridge now under construction — consequent upon the floods 
of last vear — would be undertaken in reinforced concrete. 

It seems to us that surely these doubts and fears are somewhat groundless — 
given, of course, that all due care is taken in the designing and carrying out 
of the work. These are, of course, absolute essentials ; without them, failure 
might equally well result with any other form adopted. 

In the United States and on the Continent bridges of far greater magnitude 
and span have been carried out in reinforced concrete, and have not only proved 
a success from the practical and economic point of view, but many of them are 
of artistic merit, and those of our readers who have read our journal regularly 
will no doubt have seen the numerous illustrated articles on such structures 
carried cut abroad. We would mention also the new reinforced concrete bridge 
762 ft. long opened e;irly last year in New Zealand over the Ruamahunga River 
near Featherstone. 

In our own islands the YVaterford Bridge, 700 ft. long, on which an article 
appears in this issue, should not be overlooked. We could quote many other 
examples if space permitted. 

In conclusion, we would only express the hope that the fears of those who 
have such work under consideration may be allayed after a careful study of the 
matter. 

As before repeated, with careful designing, good workmanship and super- 
vision in construction, careful selection as to the reinforcement best suited for 
any particular structure, and care in the mixing of the concrete, bridges erected 
with this material will not only prove satisfactory, but be more durable and 
will cost less to maintain. 

BELGIAN NATURAL CEMENT. 

Some interesting new departures have been made in the new specification issued 
last year by the Administration of the Belgian State Railways, which will in 
future govern the acceptance and testing of Portland cement for all works 
carried ou1 for thai Department. 

The new regulations require that all cement supplied shall be slow-setting, 
and may be manufactured by any method so long as it complies with the follow- 
ing requirements : — 

((() The chemical composition shall he such that the proportion of magnesia 

154 



&engweerTno-1 BELGIAN NATURAL CEMENT. 



(MgO) shall not exceed 3 per cent. ; that of sulphuric acid (SO s ) shall 
not exceed 2.1 per cent. ; and that of the insoluble residue shall not 
exceed 1 .1 per cent. 
(/)) No slag or other foreign matter may be added to the cement except such 
proportion of plaster as may be necessary to regulate the setting time. 

(c) The loss on ignition shall not exceed 3 per cent. 

(d) After calcination the cement must not contain less than 61 per cent. 

of lime (CaO). 

(e) The fineness shall be such that the residue on the sieve of 76 meshes 

per square inch shall not exceed 5 per cent. 
(/) The cement shall not commence to set in less than 45 minutes after 

gauging, nor be complete in less than 4 nor in more than 14 hours. 
(g) The specific gravity must not be less than 3*07. 

(h) The tensile strength of sand briquettes (3 of normal sand to 1 of 
cement), after 24 hours' hardening in moist air and 6 days' immersion 
in water having a temperature ranging between 59 and 64J Fahren- 
heit, shall not be less than 184J lbs. nor less than 284 lbs. per square- 
inch after 27 days' immersion. 
(/) Pats of neat cement gauged on glass plates shall, after 21 hours' harden- 
ing in moist air, be subjected to a steam bath, in which the tempera- 
ture of the water shall be gradually raised so that at the end of the 
first hour it shall not exceed 176 Fahrenheit, after which it shall be 
raised to boiling-point and maintained thereat for 5 hours. The pats 
must not show any cracks or distortion after this test. 
In any case of doubt concerning the quality, the officer in charge may require 
compliance with additional tests as under : — ■ 

(7) The compression strength for mortar cubes (3 to 1), after 24 hours' 
hardening in moist air and 6 days' immersion in water having the 
same temperature as for the tensile tests, shall not be less than 
1,846 lbs. nor less than 2,840 lbs. per square inch after 27 days' 
immersion. 
(k) The Le Chatelier test shall not show an expansion greater than 6 milli- 
metres. 
The officer in charge of the work is, however, given discretion to accept cement 
which falls slightly below the foregoing requirements, provided, however, 
that in no case the specific gravity be less than 307, the tensile strength less 
than 156 lb. and 227 lb. respectively at 7 and 28 days after gauging, and the 
compression strength not less than ten times these figures, but in such cases 
an extra quantity (not less than 25 per cent.) of cement must be used. 

The Administration has also issued supplemental regulations defining the 
methods by which each test shall be carried out. These exhibit a desire to 
ensure great care and absolute uniformity in the work. The diameter of the 
sieve wire is defined, the exact method of determining the specific gravity is 
prescribed, the manner of ascertaining the " normal consistency " of the mortar 
by a needle instrument is carefully regulated, the grain or texture of the normal 
sand is also provided for, the setting time is to be determined by a needle of 
given weight and dimensions, the size and thickness of the tesl pats is 
carefully fixed, and the method of gauging the briquettes and cubes is also 
strictly regulated. In this last-mentioned detail the Belgians have chosen to 

«55 



BELGIAN NATURAL CEMENT. [ CONCRETE) 

copv the German example rather than the English. In the British standard 
specification, as is well known, it is stipulated that the gauging shall be done 
entirely by hand, and the mortar pressed into the moulds without mechanical 
ramming; but the Germans adopted mechanical ramming as the standard 
method more than a quarter of a century ago, and, after prolonged experience 
of it, remain convinced that, though it may differ in greater degree from the 
conditions obtaining in actual practice than when the work is done entirely 
by hand, the advantages of uniformity of handling (as between each indiyidual 
sample tested) more than outweigh the theoretical objections, and they have 
therefore retained the mechanical principle in their new normal specification 
issued rather more than a year ago. The Belgians haye now followed suit, 
and stipulate for the ramming of the briquettes by 120 blows from a hammer 
weighing 2 kdogrammes falling from a height of 25 centimetres, and for the 
ramming of the cubes by 150 blows of a hammer weighing 3 kilogrammes and 
falling from a height of 50 centimetres. The briquettes are to be broken in a 
Miehaelis machine, but no special make of machine is named for the com- 
pression tests. 

It will be noted that a minimum iime content is insisted on, and, when 
taken in conjunction with an absolute minimum specific grawity of 3'05, even 
when the extra proportion of cement is a condition of permission to use it, 
this will effectually exclude the so-called " natural cements " from use on the 
State railwavs of the country of their origin. As it can hardly be supposed 
that the Government engineers refuse to avail themselves of these cheap 
national products without good reason for such a course, their example should 
command the careful attention of every professional man. If Belgian 
" natural cement " is not good enough for use by the Belgian public authori- 
ties, how can any of our readers dream of accepting it for use outside its 
natiye land? And yet we hear now and then of a few officials who remain 
indifferent alike to the Belgian Goyernment's own example and to the teachings 
of experience, and take no pains to insist on their contractors using only 
genuine artificial cement — the only material entitled to the description of 
" Portland cement " — on work under their control. A word of caution on this 
point is just now especially necessary, in view of the fact that, owing in part 
to the higher cost of materials, fuel, labour and freight rates, and in part to 
the end of the prolonged depression and a closer balance between production 
and consumption, the market price of the genuine article has risen considerably, 
not merely in the United Kingdom, but in other countries where cement is 
produced in large quantities; and there is, therefore, a greater temptation for 
unscrupulous contractors to employ the low-priced, but vastly inferior, 
" natural cement " emanating from Belgium, and masquerading under the 
high-sounding but utterly false title of " Best Portland Cement." 

OBITUARY NOTICE. 
Julius Homan. 

We regrel to haye to announa the death of Mr. Julius Homan, of Messrs. 
Homan and Rodders, who died in the beginning <>l February, in his 91st year. 
He was one of the pioneers in. steel and concrete construction and stated to be 
the inventor of compound girders, consisting of joists and plates, which he 
patented about 1868. lie only recently retired from business — i.e., iqi2 — and 
was well known lor his indefatigable industry and grea1 tact. 
,56 



1 



CON.MI'ULTIONAII 
KNGl Nt-EKlNC. — J 



WA TERFORD BRIDGE. 



^^^P^fel WATERFORD 

BRIDGE. 

By ALBERT LAKEMAN. 

The foLoiving article on the Waterford Bridge, "which ivas opened last month, should 
be of considerable interest at the present time, ivhen various municipalities and corpora- 
tions are discussing the erection of neiu bridges or the enlarging of old ones, and in -vieiu 
of the fact that considerable doubt still seems to exist on the strength and safety of 
reinforced concrete bridges as compared 'with those constructed of other materials. — ED. 



1 




•-.:■' 



This is an interesting example of reinforced concrete work, as it forms the 
most important bridge constructed with this material in the United Kingdom, 
and it is estimated that a considerable saving was effected by the adoption of 
the present scheme as compared with the steel bridge at one time contem- 
plated. 

The old bridge which crossed the River Suir was constructed of timber, 
and as the new bridge was to be constructed in the same position it became 
necessarv to form a temporary timber structure for the conduct of the traffic 
across the river during the period of reconstruction. This temporary bridge 
is just over 700 ft. long, and it has a width of 28 ft. between the parapets, 
thus giving a 20 ft. roadway and an 8 ft. footpath, while an opening portion 
40 ft. clear is provided for the passage of vessels. The whole of the work 
of the temporary bridge was carried out in about four and a half months, and 
this must be considered a very creditable performance when the size of the 
structure and the great length of the piles are taken into account. Some of 
the piles were no less than 66 ft. long, and the difficulty of pitching these in 
deep water with a fast current running was considerable. The vertical piles 
were driven in sets of three by the main piling engine, and the triple pile driver 
was capable of being worked with a cantilever projection of 25 ft. beyond the 
support formed by the last completed trestle of the temporary bridge, and this 
allowed the gantry to be almost continuously moved forward. The raking 
piles on either side were driven by a single pile driver, which moved forward 
on rails behind the gantry, and which was swung round to work on either side 
as required. Upon the completion of the temporary bridge the old structure 
was closed to traffic and demolition was commenced by the contractors. It 
is interesting to note that the old piles when extracted were found to be pointed, 
and had only penetrated the river bed from 4 ft. to 8 ft., the latter being the 
maximum, while the piles in the new reinforced concrete bridge are driven 
down to a depth of at least 20 ft. below the river bed to the solid rock, and 
the cvclinder piers are sunk to a depth varying from 6 ft. to 10 It. 

157 



ALBERT LAKEMAN. 



EH2ETH 




The new rein- 
forced concrete 
bridge is constructed 
on the Hennebique 
system in accordance 
with drawing's and 
specification p r e - 
pared by Mr. J. S. E. 
d e Y e s i a n , 
M.Inst.C.E., on be- 
half of Messrs. L. G. 
Mouchcl and Part- 
ners, Ltd., of West- 
minster, while the 
engineer to the 
Bridge Committee is 
Mr. A. M. Burden, 
M.Inst.C.E., t h e 
County Engineer of 
K i 1 k e n n y. The 
method of preparing 
the work for the 
bridge is worthy of 
notice, as the con- 
tractors established a 
large manufactory 
close to the site and 
employed local 
labour for the pre- 
paration of the con- 
structional members, 
the cement and steel 
only being brought to 
the works ; thus the 
execution of the 
scheme gave much 
benefit to the popula- 
tion of Waterford. 
The works were 
established about half 
a mile from tin- site 
of the bridge on the 
upstream side on the 
bank of the river, and 
the transit of the 
various members when 
completed was there- 



I&'SS~ L 1 WATERFORD BRIDGE. 

fori.' a comparatively simple matter. A large platform was built for the moulding 
of the reinforced concrete piles, and this was executed by forming rough concrete 
walls i2 in. thick at 4 ft. centres, upon which wooden plates were placed to 
carry the 9 in. by 3 in. grooved and tongued planks, constituting- a perfectly 
level bed for the lower surface of the piles. The piles are 16 in. square, and 
the shuttering for the sides was made of two 8-in. by 2-in. boards placed on 
their edges and super-imposed with 7 in. by 1 in. cleats to connect same 
together. The shuttering was held in the vertical position by means of folding- 




Fig. 3. Plan. of Cyclinder Pier. 
The Waterford Bridge. 

wedges at the bottom and distance pieces 5 in. long at the top. The total 
number of piles required for the work was 217, and these varied in length 
from 45 ft. to 65 ft., the consequence being that a considerable area was 
required for the moulding platform. In order to avoid a platform of excessive 
size the piles were moulded in three tiers, with 1 in. boarding placed between 
the first and second and second and third tiers. All the piles were made in 
about ten weeks, and each one was clearly numbered at the end to facilitate 
its transport to the required position in the work. When the piles were com- 
pleted the process of moulding the pier cyclinders was commenced, and these 

159 



ALBERT LAKBMAN. 

n r 



(CONCRETE! 



: i 




160 



£ 



CON.STRUCTIONA 
ENGINEERING 






\ VA TER FO R I) B R IDG E . 



were made in lengths of 6 ft., c) ft., and 12 ft.; two sizes being required, one 
of which has a diameter of 5 ft. 6 in. and one of 7 ft., the thickness of the 
shell being 4 in, only and well reinforced with longitudinal and circumferential 

rods. This reinloi cenienl was firstly built up in the form of a Cage, and then 
lowered by means ol a crane into the bottom ring of the timber mould, which 
consisted of a core formed of two semi-circular cradles fitted together with a 
separate outer case, also in two halves, which was arranged to give an annular 
space of 4 in. between the inner cure and the outer form. The cores and 
shells were made in lengths of 3 ft., and consequently two or more lengths were 




Fig. 5. Detail of Machinery Chamber. 
The Waterford Bridge. 

used on the top of one another to give the required length to the cylinder. 
The power for the concrete mixer and other plant was supplied by a gas engine 
of i8i h.p., and the slinging of the various materials was accomplished with a 
10-ton steam derrick crane mounted on movable bogies. 

When the work to the new bridge was commenced the various moulded 
members were slung into barges and transported to the site without any 
delay, and the execution procec ded very rapidly. The drawings illustrated in 
Figs. 1 and 2 give the general plan and elevation of the reinforced concrete 
work, and it will be seen that an opening portion 80 ft. wide is pr 

161 



ALBERT LAKEMAN. 



[CONCRETE! 



the centre for navigation purposes, and on either side of this opening- portion 
the bridge is divided up into six equal bays by the river piers, which are spaced 
at 46-ft. 4i-in. centres. The total size of the bridge is 700 ft. by 48 ft. between 




Fig. 6. Shuttering for Beams. 




Reinforcement to Cyclinder Piers. 
The Waterford Bridge. 



the parapets, giving a 32-ft. roadway and two 8-ft. footpaths. The piers arc 
placed in rows ol four across the width of the bridge, and these carry the four 
lines of main girders, which occur in each bay on either side of the opining 

167 



j„CON>TPUCTIONAU 
ft. EN01MKl'.HtNG-^, 



WATERFORD BRIDGE. 



portion. The piers were formed by driving the [6-in. sq. reinforced piles in 
groups down to the solid rock, which was encountered al the average depth 
of 30 ft. below the bed of the river, and the cyclinder rings were then p 
over these and lowered to the river bed, which had previously been dredged by 




Fig. 8. Beam Reinforcement in position. 




Fig. 9. General View of Work in progress. 
The Waterford Bridge. 



means of a grab to allow the cyclinder to penetrate the required distance; the 
bottom ring having also a cutting edge to assist in the sinking. When the 
bottom ring had been lowered it was carefully levelled and wedged in po 
by a diver, and the successive sections were lowered and connected I 

163 



ALBERT LAKEMAN. 



(concrete; 



of socketed joints, which were formed in the casting- of the various parts. A 
plan of one of these cyclinder piers is illustrated in Fig. 3, when it will be 
seen that seven piles are grouped inside the cylinder, the outside diameter 
of the latter being 7 ft. and the thickness 4 in. This size was employed for 
the piers on either side of the navigation opening, of which there were sixteen 
altogether, the remainder of the piers containing three piles only and having 
an outside diameter of 5 ft. 6 in. The depositing of the cyclinder rings con- 
tinued until the level of the low water bracing was nearly reached, and the 
interior of the pier was then filled in solid with concrete, which was delivered 
through a 12 in. diameter pipe. The bracing members are arranged in pairs, 
and they are made 36 in. deep and 18 in. wide, being moulded in advance, 
with the longitudinal reinforcement left protruding for carrying into the 
concrete filling of the cyclinders, where it was securely anchored. The high 
water bracing consists of similar members, the depth, however, being 30 in. 




Fig. 10. View showing Bracing to Cyclinder Piers. 
The Waterford Bridge. 

only, while the main girders also obviously assist in the bracing. The 
evclinders above the pile heads are continued as columns reinforced with seven 
lines of vertical reinforcement tied with transverse links spaced 12 in. apart, 
and a finish is formed with circular moulded capitals, which were cast in the 
contractors' yard. 

The main beams carrying the roadway have a span equal to the distance 
apart of the column .—viz., 46 ft. 4^ in. — and they are of two types, as illus- 
trated in Figs. 4 and 4a. The outside beams are 5 ft. 6 in. deep and 16 in. wide, 
well reinforced, as shown in the drawings, while the two inside girders, which 
are coincident with the lines of the inside piers, are 4 ft. 2 in. deep and 16 in. 
wide. The centering for the moulding of these beams was carried by steel 
joists packed up by timber from the low water level bracing beams. The 
transverse beams are placed a1 3 ft. s] in. apart centre to centre, and these 
are 14 in. dee]) and 7 in. wide, exclusive of the decking slab, which is 5.I in. 

164 



I 



CONSTBUCTIONA 
ENG1NEEK1NC 



JjaEI 



WATEUFOR1) BRIDGE. 



thick. The footpaths are carried by the outer main beams, and also by the 
alternate transverse beams being cantilevered out, as the footpaths project 
beyond the outer face of the former, and, in fact, the inner edge of the footpath 

is coincident with the inner face of these beams. The machinery for the 
manipulation of the opening portion is accommodated in four machinery 
chambers constructed in reinforced concrete at each corner of the opening, as 
shown in Fig. 5. The outer walls of these are only 4 in. thick, and two contain 
an upper floor for the storage batteries. The new bridge at the north end is 
connected to the new reinforced concrete viaduct, which was constructed a few 
years ago in front of the Great Southern and Western Railway, and at the south 
end the approach is joined up to the existing quay wall, which was not 
disturbed. The parapet is very effectively designed, as will be seen in the photo- 
graph of the finished work, illustrated in the frontispiece, and the pedestals 
occurring over the columns are bold and appropriate. The bridge is protected 
at the navigation opening by dolphins constructed of timber, and secured with 
piles driven at least 20 ft. into the river bed, while the cyclinder piers along each 
side of the opening are moulded with special provision for the attachment of 
timber fenders. 

The gradient of the bridge roadway is approximately 1 in 31 on either 
side of the opening span. The structure is designed for vehicular traffic with 
axle loads up to 16 tons, but on completion it will be tested with the dead super- 
load of 210 lb. per sq. ft. on the footpaths and two rolling loads of 32 tons 
each on the roadway. The specification demands that these loads shall be 
borne without causing any defect, without causing deflection greater than 1-600 
of the span, and without causing appreciable permanent deformation. 

The contractors for the work were Messrs. Kinnear, Moodie and Co., 
and the two rolling-lift spans were constructed by the Cleveland Bridge and 
Engineering- Co. 




Fifi. 11. General View of Temporary Bridge. 
The Waterford Bridge. 



,6 5 



JOHN A. DAVENPORT. 



[CONCRETE] 




H 



ECONOMICAL SLAB 
REINFORCEMENT. 



fc^. 



By JOHN A. DAVENPORT, M.Sc, A.M.Inst.C.E. 

The follotving article should be of interest to those of our readers ivhose 'work includes 
the designing of concrete slabs. — ED. 



In the majority of cases reinforced concrete slabs are designed for uniformly 
distributed loads and for equal and continuous spans. In fact, the R. LB. A. 
Report only considers definitely continuous slabs which are of equal spans and 
carry uniformly distributed loads, and recommends that, for such conditions, 
the bending moments at the centre of the span and immediately over the sup- 



ports shall be taken as + 



wV 

12 



this in order to allow for any settlement of the 



supports. Thus the moments of resistance of the slab sections at the centre of 
the span and over the supports must be equal in magnitude, and as the thick- 
ness is the same throughout, it follows that the area of steel at each of these 
points will be the same. 

It is not the object of this article to discuss what ratio the area of the steel 
to the area of the concrete should be for maximum economy ; but, assuming 
that this be known, it is proposed to deal with the most economical method of 
arranging the bars. The complete design involves the calculation of slab 
thickness, the calculation of the area of steel in a certain width of slab, and 
the arrangement of the reinforcement as bars of a certain section and length 
spaced at definite intervals. The choice of section, size, and spacing of bars is a 
very simple matter and requires no further notice, but the determination of the 
lengths of the bars provides a means of making the design economical or 
otherwise. In deciding upon the lengths of the bars the following points should 
always be considered : — 

i. The reinforcement should be near the bottom surface in the middle section 
of the span. 

2. The reinforcement should be near the top surface in the section over the 
supporl s. 

3. The full area of the bars is required only in mid-span and immediately 
over the supports. 

4. At intermediate points a smaller area will suffice. 

5. At some intermediate point (the point of contrallexure) no tension rein- 
forcement is required. 

6. In all ordinary cases no shear reinforcement is necessary. 

Points 1 and 2 follow from the fact that the whole of the tension is taken by 
the bars, which must therefore be placed near the tension surfaces of the slab. 

166 



(lllllgljlgjl ECONOMICAL SLAB REINFORCEMENT. 

Points 3, 4 and 5 follow from the fact that the bending moment has 
numerically maximum values at Only two points in the span, and is zero at the 
point of contraflexure. 

Regarding point 6, the R.I.B.A. report states thai shear reinforcement is 
not generally necessary in slabs. Apart from this official statement, however, 
it will be found that die shear force at the point of contraflexure, the only point 
at which there should be a break in the bars, is less than the maximum shear 
force which occurs at the support, and much less than the shear resistance of 
the concrete. The distance of the point of contraflexure from the support is 
taken by the writer as quarter the span, but provision is made for a fairly 
large deviation. Since the shear forces can be safely resisted by the concrete, 
it therefore follows that tension reinforcement only is required, and it is not 
necessary that the top bars shall be connected to the bottom bars. 

The following method, of which two alternatives are given, has been used 
by the writer for the last three years, and has always proved efficient, 
economical, and convenient. It is applicable to bars of any section or size, so 
that it may safely be used for patent bars or commercial sections. 

1st ALTERNATIVE. 

All the bars, except those which lie at the underside of the slab in the end 
spans, are of length equal to half the span plus 2 or 3 in. at each end, bent up 
or down to provide anchorage. The bottom bars in the end spans have straight 
lengths equal to three-quarters of the span plus 2- or 3-in. bent ends. If the end 
ot the slab be fixed in a wall chase or in any other manner, alternate bottom bars 
are bent up to the top, as shown later, to resist any tension which occurs in the 
top of the slab. 

All the bars, top and bottom, are arranged symmetrically about the sup- 
ports and centres of spans, so that the end of the straight length of a top bar 
is vertically over the corresponding end of a bottom bar. They are then 
staggered a distance equal to the nearest 3 in. to one-tenth the span, alternate 
bars going right and left, as seen when looking across and not along the bars, 
and this gives the final arrangement. 

This results in the full area of the bars for lengths of 0*3 of the span over 
the supports and in mid-span, and one-half the area for lengths of or of 
span about the points which are distant quarter of the span from the supports. 
It also allows the point of contraflexure to deviate an amount equal to o'i of 
the span on either side of the quarter-point. 

In the foregoing description the bars are first arranged symmetrically and 
then staggered, but it will be found in practice that they can be correcdv 
staggered when first put in, provided the right workmen and foreman arc on 
the job. 

Taking as an example a continuous slab of u-ft. span, the amount of 
staggering must be 1 ft. 3 in. ; the length of the intermediate bars o ft. plus (1 in. 
for two bent ends; and the length of the end bars 9 ft. plus 6 in. for two bent 
ends. 

The arrangement is shown in Fig. 1, in which, the plan shows, to an 
exaggerated scale, alternate bars lettered A and B. The correct disposition of 

c 167 



JOHN A. DAVENPORT. 



[CONCR ETE] 



the bars relatively to the supports is shown in the sections with bar A above 
and bar B below. The details of the bars are given in Fig. 2, in which C shows 
top and bottom bars for all parts except in the bottom of the end spans, D 
shows the bottom bars in the end span when the end is not fixed in any way, 
and E shows alternate bottom bars in the end span when the end is fixed. 
Notice that the total lengths of the bars D and E are the same. 




This arrangement results in the following disposition of the reinforcement, 
see Fig. 1. 

Over the supports and in the intermediate spans the total area of metal 
required by the design occurs for a length of 3 ft. 6 in. 

In the same parts not less than half this area occurs for a length of 
8 ft. 6 in., so that there is tension reinforcement for a continuous length of 
nearly three-quarters the span. 

In the end span the full area of metal occurs for a length of 7 ft. 9 in., and 
not less than half this area for a length of 10 ft. 3 in. 

Further, the point of contraflexure may occur anywhere in the space X, 

which has a length of 2 ft. 6 in. 



sh 



6-0" 



p<r 



7'-3" 






If the points 1 to 6, already noted, 
be compared with this arrangement it 
will be found that the reinforcement is 
disposed in the position and manner 
Fig. 2. in which it ("an best resist all the 

tensile forces. 
The advantages which result from this arrangement are : — 

(a) All the bars, except those in the end spans, being of the same length 
means that the steel order is of the simplest form, and there is no risk of putting 
in, at any particular place, bars of the wrong length. 

(b) As all the bars are straight, with short bent ends only, the work involved 
in bending is the easiest possible, and there is no risk of bends being put in the 
wrong plai - , 

(1 i As all the bars are comparatively short they are easy to handle, and there 
is no risk of accidental bends or kinks. 

(1/) A> top and bottom bars are not connected together, no templates for 
holding up the bars are required. 

168 



fo T CON>TKUCTIONAlJ 
'A LNOIMEEKING — J 



ECONOMICAL SLAB REINFORCEMENT. 



(c) The laying of bars and concrete can go on together, and no replacing i> 
necessary as would be Bhe case if the bars were laid first. 

(/) The weight of steel ran be calculated from a very simple formula. 
(g) The cost of laying slabs is reduced to an absolute minimum. 

The method of laying the slabs as used by the writer is as follows : 
After the centering is ready, a sufficient number of bars arc laid handy for 
the stretch to be concreted. The thickness of the cover is then laid and the 

SECTION A 



L+T 



I r 



V 



1 [ 



tJ 



V 



LU 



bnttom bars immediately placed in the correct positions on the concrete. Further 
concrete is added till the surface has reached the level of the top bars; these are 
then laid and the slab completed. 

2nd ALTERNATIVE. 

The foregoing arrangement has had to be altered at times to meet the 
wishes of surveyors and architects, whose sole objection was to the discontinuity 
of the top and bottom bars. To overcome this objection adjacent top and 
bottom bars are connected by means of a b" (or 4") diagonal, the resultant 
arrangement being the same as before, except for this. In order that the bars 
in any part may be connected to the bars in adjacent parts, alternate bottom 
bars are .all connected to the corresponding top bars on the right, the inter- 
mediate bars being connected to the top bars on the left. Thus, apart from 



C\t 



& 



D^: 



D.v: 



bars in the end span, the total straight length of any bar is now twice what it 
was formerly. The advantages are the same as before, except that provision 
must be made to hold up the bars, and the longer length is not so convenient. 

Figs. 3 and 4 show details for a slab of 12-ft. span corresponding to Figs. 
1 and 2. In the end spans only alternate bottom bars are connected to the 
t >p bars, so that there are three lengths of bar instead of two as before. It 
will be noticed that in any set of bars, bottom or top, adjacent bars are 
nected right and left, SO that the slab is tied from end to end in a width < 
to twice the pitch of the bars. 

The details of bottom bars for fixed end spans are no! separately shown, 
being already given in Fig. 2. 

c 2 169 



JOHN A. DAVENPORT. [CONCRETE ) 

Weight of Steel. — Taking first a bar running from end to end in the 
direction of length of the bar, the length of bent ends in any span will be 
4 x ^ — 12 in., or i ft. For 2-in. bent ends this will be 8 in., but 3-in. ends 
are only considered now. The straight length in any span will be equal to the 
span, so that the total length of bar in one span will be 1 ft. longer than the 
span. 

Now let L-^ total length of slab in feet, measured in the direction in which 
the bars run. 
B = total breadth of slab in feet in the perpendicular direction. 
n = total number of spans. 
p = pitch of bars in inches. 
Then the total length of one bar will be L + n feet, and the number of 

1 ^B. 
bars in breadth B will be - 

P 
The total length of bar in the slab will be the product of these two quan- 
tities— i.e., l -^- (L + n) feet. 
P 
Now let .1 be the area of one bar, then, taking 3*4 lb. as the weight per 

foot run of 1 sq. in. of steel, the weight of the slab metal becomes 

U \L-rn) tons. 

2240^ 



or 



W= O'OIS^^ (L+n) tons. 



P 

Taking a slab of 200 ft. length and 150 ft. breadth, divided into 20 spans 

of 10 ft. each, with j-in. diameter bars at 6-in. centres — 

L = 200 

n — 20 

p = 6 

A =o"ig6 

ir = (V0lx2 X 150XO ' 196 (200^20). 
6 

_ 0"0182X150XQ T 96X220 

6 

= 19'62 tons. 

The product 3*4 .1 gives the weight per foot run of the bar, und if this 

figure be preferred it may be used after slightly modifying the formula above. 



170 



I 



CONSTRUCTIONAL) 
ENGINEERING J 



CONCRETE ROADS AND FOOTWAYS. 



> ,>*'■-...:, y' :•■; *..- 









s&*&-.^ 



£2* ,H-..^,.- -Hi,- < '"^f_2? 



4jsi! 




CONCRETE ROADS AND 
FOOTWAYS. 



By E. R. MATTHEWS, A.M.Inst.C.E.. F.G.S. 

Boron ih Engineer of Bridlington, 

The question of the use of concrete for roads is receiving considerable attention in the 
United States, though it has only been used to a minor extent in this country. 

We propose in subsequent issues to publish some further articles and papers on this 
subject, as it is one luhich merits a great deal more attention than is at present accorded 
to it. —ED. 

While footways constructed of concrete in situ have been formed in various 
parts of this country — and the author has had a good deal of experience in the 
construction of this class of footway, Fig. 1, for example, representing one 
of this type recently formed by him at Bridlington — nevertheless the use 
of this material in the formation of roads has, with a very few exceptions, 
not been adopted. The advent of the motor car upon our roads has necessitated 
the introduction of methods of construction which in the days of the horse- 
drawn vehicle would not have been thought of. A. loosely-bound road surface 
is no longer of any use, for the rapid car has a tendency to tear out the metal 
even from a compact road surface. Concrete, therefore, is the latest material 
used in road construction, and it is the intention in this article to describe its 
use in America, for it is that country that has taken the lead in the use of 
this material. It is proposed to set out some of the advantages and disad- 
vantages of using this material. Figs. 2 and 3 represent cross-sections through 
concrete roads and footways as recommended by the writer. 

ADVANTAGES. 
(I ) Durability. — The chief advantage of a concrete road is that its life is 
greater than that of almost any other road, with the exception of perhaps 
granite and whinstone setts. The nature of the material of which the road 
is constructed is such that it increases in hardness and durability with age. 
This cannot be said of any other material. 

Wood blocks become soft and often wear unevenly ; stone setts, unless 
of granite or whinstone, vary in hardness, and fail in the same respect ; granite 
macadam has to be renewed where there is heavy traffic on a road every three 
years or so, in some cases oftcner ; tar macadam can only stand light traffic, and 
then it has to be renewed every few years ; but a concrete road will present as 
good a surface at the expiration of five years as on the day the road was 
completed. 

Under these circumstances, and knowing the various purposes for which 
American engineers have used concrete, we are not surprised to find that at 
present time there are in America under construction some hundreds of miles of 

! 7 I 



E. R. MATTHEWS. 



(CONCRETE) 



concrete roads, and that the New York State Commission of Highways are 
constructing - about 200 miles of such roads, 50 miles of which are in the 
Rochester division. The California State Engineering Advisory Board also 
have 56 miles of concrete roads in hand. 

(2) Uniform Wearing of Surface. — Unlike other methods of road construc- 
tion, a concrete road wears uniformly, and not in holes as is the case with 
an ordinary macadam road ; this is a Aery important matter. 

(3) Cleanly Appear= 
ance. — A road of tins 
class always presents a 
cleanly appearance, and 
can easily be cleansed by 
playing a hose upon it, or 
watering with water-carts 
and then sweeping well. 

(4) Maintenance. — 

It costs practically nothing 
to maintain a road of this 
class. 

(5) Economical. — 

The cost of constructing 
such a road is no greater 
than that of a tar mac- 




adam road, as will be 
shown later. 

DISADVANTAGES. 

(1) Non-Elasticity. 

—The principal of these is 
that the extreme hardness 
and non-elasticity of the 
road make it somewhat 
injurious to horses using 
it, especially when the 
animals stand daily for 
hours upon the road, as in 
the case of a cab horse. 

(2) Inclined to be 
slippery. — Unless the 
greatest care is taken a 

road of this class in certain weather will become slippery. The surface of the 
concrete should he cut up into V-shaped grooves about \ in. deep and .', in. 
wide, so as to give horses a better foothold. A road of this type should not be 
constructed where there is a considerable longitudinal gradient. 

(3) Difficulty in Opening Out. — This is a serious objection, as the open- 
ing out of our town streets is almost a daily occurrence. 

1 his objection might be overcome to ;i large extent by the construction 



ki 11 Footway, Bridlington 



172 



J, CDNSTUlR. - TIONAi; 
£C ENGINEERING -~. 



CONCRETE ROADS AND FOOTWAYS. 



under the centre of the road of a reinforced concrete subway, which would 

accommodate gas and water mains, sewers, electric cables, telephone wires, etc., 
or these might all be laid under the footways, and the latter not be of concrete, 
but flagged or of asphalte; the disadvantage of this course is that the mains 
would have to be repeated on both sides of the road to really be of any benefit. 



+■ 



24'-0 



+ 



8-0 




Fic. 2 



(4) Somewhat Noisy. — The noise is reduced by the tarring- of the surface, 
which should be repeated every other year or every third year if there is a 
good deal of traffic on the road. The tarring will cost about ifd. per sup. yd. 

if 



r T 






r" 



Fic. 2a.- 




Fig. 5 



MATERIALS AND METHOD 
J" OF CONSTRUCTION RECOM- 
* MENDED BY THE AUTHOR. 

Concrete Road : Pro= 

portions. — The concrete 
used should be in the propor- 
tions of 5 parts gravel or 
broken granite varying from 
j in. to ih in. in size, i part 
coarse sand, and i part of 
Portland cement. A fairly 
wet mixture should be used. 

Thickness of Concrete. 

— A thickness of concrete of 
6 in. will be ample ; it should not, however, be of less thickness. 

Expansion Joints. — These should be inserted every 30 ft. The author on 
one occasion when forming a wide concrete footway omitted these, but found 
as a result that cracks appeared about every 30 ft. ; he therefore strongly 
recommends their insertion. 

Hand Tamping. — The pavement should be finished by hand tamping until 
the mortar comes freely to the surface. 

Tarred Surface. — It is advisable to tar the surface of the concrete (about 
j gall, per sup. yd.), and to spread granite or limestone screenings, and to 
repeat this a year after. 

Cost. — The New York concrete roads are costing $9,000 to $12,000 per 
mile, taking a 16-ft. road as a basis. The author estimates that such a road 
In this country would cost, including the tarring of surface, but independent ot 
the cost of preparing the foundation, which, should be formed in the sanu 
manner as for an ordinary macadam road, 3s. fid. per sup. yd. only, which is a 
low figure for a permanent road. 

Footways. — hoot ways, as shown in Figs. 1 and 2, formed of co: 

173 



E. R. MATTHEWS. [CONCRETE) 

4 in. in thickness, have cost the author, with a brick-bat foundation, but 
no tarring of surface, 2s. 4c!. per sup. yd. This is very little more than the cost 
of tar paving - , while York or artificial stone flags have cost him 6s. 3d. per 
sup. yd. laid complete. 

The footways should have a 6 to 1 concrete base with a 2-in. wearing 
surface of a : 1 cement and sand, and should be cut up into blocks, say, to 
imitate flags, or be pitted with a tooth roller. They should be brought up to 
a true face bv means of a trowel. 




Fig 4 



Kerb. — The author has usually formed this of the same material as the 
footways, but 12 in. by 8 in., and it has cost him about 3s. per lin. yd. The 
edge should have a f-in. chamfer as shown in Fig. 2a. 

AMERICAN EXAMPLE OF CONCRETE ROAD. 

A good example of a concrete road constructed recently in America is 
shown in Fig 4, which represents a road of this class just completed at Nor- 
wood, Ohio. It may be briefly described as follows : — ■ 

The concrete consisted of a 1 : 2 J : 5 mixture- -sand and crushed stone — 
in the writer's opinion it should not have been a weaker mixture than 6 to 1. 
Expansion joints (i in.) were placed transversely every 30 ft., and along each 
channel, and filled in with rubber asphalte. 

The crushed stone used varied from } in. to 2 in. in size, the sub-foundation 
consisting of cinders; the concrete was mixed by a Milwaukee mixer, and laid 
to a thickness of 6 inches, and the cost of constructing this concrete road 
worked out at $1.20 per sup. yd. Transverse expansion joints § in. in width 
and filled in with pitch were inserted at Atchison, Kansas, where 9,500 <>up. yd. 
of concrete roadway were laid last vear. 

This road cost $1.07 per sup. yd. The finished surface was covered with 
sand and kept wet for several days. 

Reinforcement. — At Detroit the concrete was reinforced by the insertion 
of f-in. round steel bars placed longitudinally and transversely at 2 ft. centres 
and within ii inches of the upper surface of the concrete. Other reinforcement 
was inserted on the underside of the concrete, and this consisted of }-in. steel 
bars laid at 4-ft. centres longitudinally and transversely ; the top and bottom 
reinforcement was connected by means of clamps. The author docs not see 
the need of inserting this light reinforcement, which adds to the cost, although 
it, of course, considerably increases the strength of the pavement, and, what is 
more important, it prevents longitudinal cracks occurring a year or two after 
the pavemenl lias been laid. 

•74 



G 



ENGINEERING — ; 



CONCRETE ROADS AND FOOTWAYS. 



The lop layer of concrete at Dctroil consisted of i : 1 : }, the bottom layer 
of i : j> : 6. Expansion joints were inserted every 30 ft. longitudinally. 

Size of Aggregate. While this at Norwood consisted of stones varying in 
size from : ( ! in. to 2 in., the author recommends a smaller aggregate, say .', in. 
to 1 \ in. in size. 

In a paper on " Concrete Roads " read by Mr. A. X. Johnson at the Ameri- 
can Road Congress in October last, he advocates the practice of using aggregate 
of not more than 1 in. in iis largest dimension, and the insertion of expansion 
joints every 40 ft. to 50 it. 

Concrete in one-course. — Professor F. P. Spalding, in his recently pub- 
lished " Roads and Pavements," advocates the placing of expansion joints every 
5c ft., and at right angles to the kerb line, and suggests that they be at least 
1 in. wide, and filled with a soft-wood strip of the same depth as the concrete. 
He recommends a one-course method in preference to the two-course in placing 
the concrete, so as to avoid a plane of weakness occurring between the two 
courses; and the author concurs in this suggestion. 

Mr. Johnson's estimated cost of a road similar to that suggested by the 
author, and shown in Fig. 3, is $1.00 per sq. yd. 

GENERAL. 

There are many patented methods of concrete pavement construction 
in vogue in America; these include the Blome Company's Granitoid Blocking 
method, the Hassam Pavement, and Dolarway Pavement. It is not the 
intention of the author to describe these, but to conclude by saying that in his 
opinion concrete will be used a good deal in this country in the future in the 
construction of roads, especially in busy town streets and in narrow back roads. 



PH. RAUER 

m ° 



THE 

INTER. 

NATIONAL 

BUILDING 

EXHIBITION 

AT LEIPZIG 

IN THE 

MAKING. 



CONCRETE! 







Bv PH. RAUER, C.E. 

In presenting the following article it is desired to draw special attention io this 
Exhibition, -with a vieiv to interesting all those concerned in this country, and it is hoped 
that at this Exhibition, -which is International in its character, England maybe ivell and 
adequately represented in the various sections. The Exhibition is to be opened in May and 
lasts until October. —ED. 



The epoch-making- success which has attended the principle of exhibitions on 
special subjects has given a new and sudden trend to the ideas which have 
hitherto governed the erection of exhibitions. Such industries as are powerful 
enough to stand alone have followed this new impulse with surprising celerity. 
The industries of building and housing, the foremost and greatest industries 
of all, and those whose roots lie deepest in the soil of domestic life, have 
combined for the formation of a first general international review, the idea of 
which has now been realised in the impending- Leipzig International Building 
Exhibition of 1913. It is characteristic of German thoroughness that the 
principle of specialisation has been fully realised in Germany, in hygienics by the 
Hygiene Exhibition, and now in architecture and housing through the coming 
Building Exhibition — that principle of specialisation which at once allows of a 
full representation of all matters in question and an efficient analysis of all 
pertinent subjects. A consistent solution of the problem of how to arrange a 
comprehensive exhibition of all matters pertaining to the departments of build- 
ing and housing also necessitates a considerable increase in the area of ground 
to b:- occupied by the exhibition. Xo less than 475,000 sq. yds. — an area 
ding thai of the Brussels Exhibition of 1910 — is necessary in order to give 
a complete, though condensed, outline of the important building industry. 

To the east of Leipzig, on the historical spot on which the great Battle of 
Leipzig was foughl in [813, the exhibition is built on hilly ground, from which 
elevated position the town of Leipzig, the seat of Germany's oldest university, 
can be overlo iked. On the other side, looking towards the easi , the eye is caughi 
and held by the colossal stone monument to the Battle of Leipzig, erected to 

I 76 



s 



CONSTPUCTIONAEJ 
ENGINEERING 



INAO 



BUILDING EXHIBITION AT LEIPZIG. 



the memory of the heroes who shed their blood here a century ago. On the 
same soil on which the nations were then opposed to each other in deadly 
combat the friendly competition, which has but a single and common goal in 
view, will now take place. 




The exhibition grounds will be divided into two portions by a broad track 
of railway lines. The larger half, that lying nearest to the town, contains the 
chief and palatial exhibition buildings; the smaller half, that on the side of i 

177 



PH. RAUER. 



[CONCRETE) 



Monument, is laid out in park-like grounds, and contains the special agricul- 
tural exhibition, and a small village, complete with agricultural buildings, 
dwelling-houses, school, and church. A special site has also been selected for 
a recreation park. 

In pleasant contrast to the want of clearness usually shown in other exhi- 




j. 


Architecture 


ii. 


Wall Surface Treatments 


iii. 


Building Materials 


iv. 


Machinery Hall 


v. 


Underground Communication 




Exhibits 


vi. 


Building Equipment ■ 


\ ii. 


Ke nforced Concrete 


Villa 


Testing of Building Materials 




Entrance A 


ixA. 


Congress Hall 


X. 


Principal Restaurant 


xi. 


Entrance B and Administra- 




tive Building 


xii. 


Hall of the Steel Workers 




Union and the nion of 




German Bridge Builders 


xiii. 


Historical Exhibit 


XIV. 


Entrance C 


XV. 


Model Farm Fuildings 


xvi. 


Small Model Vi lage 


x v i i . 


Model Cemetery with Church 


xviiA. 


Monumental Sculpture 


xviii. 


Restaurants 


xix. 


Park 


XIXA. 


Agricultural Buildings 


XX. 


Austrian Section 


xxi. 


State of Saxony Section 


x*ii. 


City of Dresden Section 


xxiii. 


Foreign Pavilion 


xxiv. 


Roumanian Pavilion 


XXV. 


Hospital Section 


xxvi. 


Principal Cafe- 


x x v i i . 


German Industries. Pavilion 


xxviii. 


Garden Approach Marien 
brunn 



Plan of Exhibition Grounds. 
The International Building Exhibition. Leipzig. 

bitions in the arrangemenl of tin- chief building's, the building's in the Leipzig 
Exhibition are clearly and comprehensively arranged in groups according to 
their relations to each other. The general building design is the work of the 
Royal Government Surveyors; Weidenbach and Tschammer. The regular rise 
in the ground from the town of Leipzig to the crowning height on which the 
Monument of the Battle of Leipzig stands has been utilised with particular 
178 



r a. CONSTWIJCTIONaLI 
1 ft. ENG1 N t.F.R I NO -~-J 



BUILDING EXHIBITION AT LEIPZIG. 



ingenuity. From the main entrance, facing towards the town, a magnificent 
thoroughfare, 40 yds. in breadth, leads straight to the Monument, the axial 
arrangement of the buildings in this exhibition city being marked by a second 
lateral lime-tree avenue, 30 yds. broad and 500 yds. in length, crossing the 

main thoroughfare at right angles. The street crosses the railway cutting, 




Administration Building. 
The International Building Exhibition, Leipzig. 

195 ft. broad, by means of a reinforced concrete girder-bridge, 8 ft. in breai 
The difference in the level of the ground here and on the farther side has been 
utilised for the formation of a terraced walk of considerable dimensions and of 
architectonic importance; At another point the railway cutting will be span 

1-9 



PH. RAUER. 



[CONCRETE] 




Old Leipzig. 



by a second reinforced con- 
crete bridge of technical 

interest, to be built on a 
new system of the editor of 
our contemporary, Bcton 
und Eisen, Dr. von 
Emperg-er, of Vienna. 

This erection exhibits 
a happy combination of 
ribbed cast-iron, natural 
steel on the Schroiff system, 
and latticed trusses without 
rivets. The use of cast- 
iron for the bearing of com- 
pression strain is techni- 
cally a feature of peculiar 
interest in the structure. In 
order to afford a coherent 
picture of the present sate 
of the entire building and 
housing industries, it has 
been decided to erect, apart 
from the industrial exhibi- 
tions and the exhibitions 



rep rcsentativc 

f different 
countries, a 
science and art 
exhibition, i n 
which all sub- 
jects and objects 
of the exhibition 
are arranged, 
for the most 
part from a 
scientific pant 

01 view, and 
without regard 
to their origin. 
i lire, owing to 
i t s carefully 
considered ;ir- 
r a n g e m ent, 
valuable fea- 
tures of interest 
are offered to 

I So 




l burcfa mi t.,e Vu 
Thk International Building Exhibition, Leipzig 



d 



C'&N^U'l JCTIONA L 
ENGINEERING — , 



BUILDING EXHIBITION AT LEIPZIG 



the \ iewof Lhe technical expert ; while, on the other hand, great care has been taken 
to make the present stage of technical developm< nt comprehensible to the layman, 
to demonstrate the results of buildings in their relation to social, industrial and 
hygienic life, and so appeal to the intelligence ol the masses, not only as 
regards general questions of technical practicability, but also in respect of the 




Principal Entrance. 
The International Building Exhibition, Leipzig. 



value of the structures from a domestic and industrial point of view. Models, 
plans, and photographs alternate with statistical explanations and treatisi 
political economy in their relations to daily life, 

The visitor to this technical and politico-economical exhibition will find hen 



PH. RAUER. 



[CONCRETE] 



a perfection and completeness of detail. Though unavoidable condensation has 
prevented historical retrospects in general from being- taken, the visitor will vet 
find such short hints in all branches of technical science, as to the orio-in and 
consequences of technical events of the past, as are necessary to an understand- 
ing of the development in the art of engineering and architectural designing. 
From the examination of the work that precedes the erection of all structures 

we pass to the ex- 
hibits of the finished 
products of the art of 
engineering, of super- 
structure, and to the 
valuation of the single 
part in its relation to 
the whole construc- 
tion. The settlement 
question ar.d the 
social and hygienic 
relations of building 
and dwelling-house 
construction are also 
H thoroughly gone into. 

-£# m JtftfS ^ whole village 

f ^ n I owes its origin to the 

idea alone of repre- 
senting the influence 
which architectural 
progress has had on 
agriculture. 

T h e reinforced 
concrete hall may 
rank as the latest 
advance in the art' of 
this form of construc- 
tion. A reinforced 
concrete hall, 113 fl. 
high, with a cupola 
having a 97-ft. span 
and carried by 16 
concrete pillars, is a further example of the applicability of this method of build- 
ing, and finds its contrast and companion in an immense tower-like building of 
iron, crowned with a ball 19 fl. in diameter. 

The exhibits illustrating the garden-city movement in the scientific depart- 
ment are represented by a garden city of 70 houses, which an 1 not temporary, 
but built to last. 

The block' of chief buildings in the Exhibition consists of extensive industrial 
halls; the industrial section comprised in them covers 23,500 sq. yds., to which 
must be added the extensive open-air exhibitions. Here also specialisation is 
182 




Thomas Church, Leipzig. 
The Interna i ional Building Exhibition, Leipzig. 



■ EjVGgjEERlNG — J 



BUILDING EXHIBITION AT LEIPZIG. 



consistently carried out. There are exhibitions for architectural art, interior 
decoration, building materials, building equipments, sport, hospital building, 
and two exhibition buildings for the machinery industry. Between the industrial 
halls stand the buildings representing foreign nations, and the pavilions of the 
various guilds, states, and authorities. In all the building and dwelling-house 
exhibitions all hygienic as well as domestic demands have been carefully attended 
to. Special exhibitions have been erected lor two branches of hygienics, and 
have aroused the widest interest — the protection of the workman at the building 
site and the whole question of workmen's provision. The section for work- 
men's provision enjoys the services of a group of eminent physicians and the 
supporl of tlie trades unions and the National Bureau of Insurance. The General 
Commission of the Trades Unions of Germany will erect a budding in a form and 
condition calculated to show the devices adopted to prevent accidents, not only 
by means of models, but also in a practical manner. 

The town of Leipzig', within whose walls a large number of important 
congresses will take place this year, also contains many other objects of interest 
for the stranger. 

Objects of interest will also be afforded for many visitors by the 
inauguration of the Monument of the Battle of Leipzig and the numerous 
features which will remind them of the historical days of a hundred vears ago. 
The largest railway station in Europe, which is destined to cope with the 
enormous traffic, has also already opened its doors. 

Nor have the peculiar historic recollections called up by the thought of 
the Battle of Leipzig in 1813 been neglected by the Exhibition. A whole town, 
with streets, squares, and alleys, represented as they were in 1813, has been 
erected with the name " Old Leipzig." 




Front View of Administration Building. 
The International Building Exhibition, Leipzig. 






HECTOR ST. GEORGE ROBINSON. 



[CONCBCTFj 




EXPERIMENTS on the 
ADHESION- OF OLD 
AND NEW CONCRETE. 



HECTOR ST. GEORGE 
ROBINSON. 



The folloiuing is a Paper ivhich ivas published in the Proceedings of the Institution of 
Civil Engineers, and is noli) gifen here in full by the k'nd permission of the Institution. — ED. 




In examining cracks in plain and reinforced concrete structures, usually caused by 
shrinkage and thermal stresses, the author has observed the frequency with which such 
cracks occur in places where concreting has been stopped for some time and then 
resumed. The difficulty of obtaining good adhesion or bond between new concrete and 
concrete already set is generally recognised by engineers, and various methods of 
treating the old surface before laying the new concrete are in vogue. 

With the object of terminating a dispute which arose in regard to the responsibility 
of a contractor for the efficiency of the joints in a fairly large reinforced concrete 
structure, the author carried out a series of experiments as to the relative efficiency 
of various methods of jointing concrete. The necessity of such tests was occasioned by 
the limited amount of experimental data available on the subject. 

In view of the great difficulty experienced in obtaining reasonably uniform results 
when fairly large concrete specimens were tested in direct tension, it was decided to 
test prisms by cross-bending. The apparatus required to carry out this type of test is 
of an extremely simple description, and it was thus possible to make the tests under 
natural conditions in the field. 

Fig. l. 




In connection with bending tests, it is important to keep in view the fad that the 
calculated stress in tension at the extreme <-clgr of a bar of square or rectangular cross- 
section is much higher than the value obtained in direct tension. In the present case 
the tensional strength or modulus of rupture is used for comparative purposes only. 

For the purpose of the experiments, concrete prisms 30 in. long and 4 in. square 

were made in timber moulds lined with /inc. The prisms were tested as simple 

cantilevers, being fixed ai one end and loaded at the oilier as shown diagramatically in 

Fig. 1. The distance from the joint to the point of application of the load was jo in.. 

184 



f lr CONSTPUCTIONA1 .1 
1<1 ENGINEERING — J 



ADHESION OF OLD AND NEW CONCRETE. 



and in arriving at the tensile stress at the joint the dead weight of the portion of the 
prism broken off was included. In testing, the prisms were reversed so that the top 
or tension side was the underside during moulding. The concrete was of uniform 
composition throughout and was made in the proportion of 2 cu. ft. of crushed Thames 
ballast, 1 cu. ft. of clean Thames sand to 45 11). of Portland cement practically a 
4:2:1 mixture by volume. The ballast was mostly crushed flint pebbles, all passing 
a *-in. mesh sieve and being retained on a 4-in. mesh sieve, the average percentage of 
voids being 34. The sand was screened from the normal Thames ballast, the grains 
being \-\n. and less, and the voids in this case being 3 1 -5 per cent. The cement was 
to the British Standard Specification and was bought in the open market. Its average 
tensile strength per square inch was as follows : — 

Neat, at 1 day ....... 243 lb. 

,, ,, 7 days ....... 625 ,, 

,, ,, 2 months ...... 76S ,, 

It set initially in 1 hour 25 minutes, the final setting time being 4 hours 30 minutes. 
In mixing the concrete, 10 per cent, of water was used, based on the total weight of 
the dry materials. Five sets of prisms were made and the conditions as to mixing and 
storing were identical. 

To arrive at a basis for comparison, a set of six prisms (reference " A ") were 
made without joints, these specimens being moulded and tested when twenty-eight 
days old. In the remainder, division boards of roughly-sawn spruce were fixed in the 
moulds 8 in. from one end and the first portion of the concrete was placed and well 
rammed. These short lengths were allowed to harden for seven days, after which the 
face against which the new concrete was to be placed was prepared and the prisms 
completed, care being taken to well ram the new material against the old face. The 
finished prisms were then allowed to harden for twenty-eight days, after which they 
were tested. 

Four distinct types of joint were investigated. In series " B " the faces of the 
seven days' old concrete were merely washed and well wetted prior to the imposition 
of the new material. As these faces had been moulded against a somewhat rough 
soft-wood board they were fairly open and coarse, and the somewhat high efficiency 
obtained with these joints is due to this roughness. The faces in series " C " were 
roughened with a chisel, all the loose material cleaned away and the surface thoroughly 
wetted. In series " D " the faces were prepared first as in series " C," and were then 
washed over several times with a thick wash of semi-liquid neat cement grout, the 
new concrete being immediately applied. In the last series, " E," the faces were 
thoroughly cleansed with water and treated with hydrochloric acid. After the acid had 

Calculated Tension at Extreme Edge, L3. per So. In 
M 
f— ~, where / is the stress in lb. per sq. in., M the bending moment in inch-pounds, and * the modulus ot section. 



Series A. 


Series B. 


Series C. 


Series D. 


Series E. 


Test No. 


So id 
Prisms. 


Test No. 


Face 
Wetted 

on'y. 


Test No. 


Face 

Roughened 

and 

Wetted. 


Test No. 


Face 

Roughened 

and 

Grouted. 


Test No. 


Face 
Treated 

with Acid. 


A 1 
A 2 
A3 
A 4 
A 5 
A6 


3°2 

362 
289 

340 

352 


B 1 
B2 
B3 
B 4 
B5 
B6 


140 

78 

130 

no 

172 


OOOOOO 


194 
170 
205 
142 
165 
234 


D 1 
D 2 
D 3 
D 4 
D5 
D 6 


325 

272 
280 
248 


E 1 
E 2 
E3 
E4 
Es 
E 6 


300 
248 
260 
201 

271 


Average 


329 


- 


126 


- 


185 


- 


281-25 


— 


270 


Efficiency t ioo % 

' 1 


— 1 38-3 % 


56-3 % 




85-5 °o 








HECTOR ST. GEORGE ROBINSON. [CONCRETE] 

rerrtcved the cement to a sufficient depth to expose the aggregate and thus leave a very 
rough face, all traces of the acid were removed with stiff brushes and water and the 
new concrete was then applied. 

The results of the tests are tabulated in the accompanying table. Prisms A4 and 
B5 were defective, while prisms D2 and D6 broke outside the joint, therefore these 
cases have not been included in the table. All the other specimen- broke wholly or 
partly at the joints. The average efficiency of the various joints in the table is given 
in relation to the strength of the unjointed prisms. 

While these tests are somewhat limited in scope, it is evident that there is a a n- 
s'derable difference in the strength of the various joints. The value of roughening and 
grouting i- ch arly apparent. The joints treated with acid show a high efficiency, but 
the trouble and care necessary for the successful use of acid, especially where an 
aggregate of a porous nature i> used, is opposed to its adoption in actual practice. 



186 



E 



, CONSTPUCTiONAT 
ENG1 PEEKING — j 



LAW REPORT. 




SHUM\N'S CONCRETE PILE 
PATENT UPHELD. 

The following is the report of some proceedings of general technical interest, heard at the 
Royal Courts of Justice, London. At the time of going to press an appeal has been entered. 



The case of Simplex Concrete Piles, Ltd., v. J. and \Y. Stewart* came on for hearing 
before Mr. Justice Neville on February 4th and 5th. The action was brought for 
infringement of Frank Shuman's Letters Patent No. 9025** A.D. 1904, of which the 
plaintiffs are the registered proprietors. The Specification had been twice amended. 
First, in view orf J. Potter's Patent No. 1124 A.D. 1864, which describes a method of 
(-instructing piles by first sinking a tubular pile with a loose tip or point, filling the 
tube with artificial stone composition, and then withdrawing the tube, the supply of 
fresh composition being kept up as the tube was withdrawn. The tip was left in the 
ground and formed a foundation for the pile. The drawing shows a tip of the same 
dismettir across the top as the tube. On this amendment the original second claim 
was cut out and a disclaimer inserted to restrict the first claim, which was of a broad 
nature. By the leave of the Court, a second amendment was made, by which the 
first claim was abandoned; and the original third claim is now the only one. With 
certain abbreviations, the Specification now stands as follows, the claim being given 
in full : — 



The invention relates to that method of 
forming piles of concrete or cement which 
consists in first driving a preparatory pile 
into the ground and then withdrawing the 
said preparatory pile and filling the open- 
ing formed thereby with concrete or cement 
in a fluid or plastic condition which, when 
it becomes set, forms the permanent pile. 
The object is to fill the openings with con- 
crete or cement in a better manner than 
heretofore and produce a better pile. In the 
accompanying drawing, Fig. 1 is a vertical 
section illustrating the method of forming 
the opening in the ground by means of a 
preparatory pile, and Figs. 2, 3 and 4 illus- 
trate successive stages in the formation of 
the permanent pile. 

The preparatory pile consists of a metal 
tube 1, provided at its top with a driving 
head 2, and at its bottom with a point or 
end-piece 3, which is detachable from the 
tube 1, and is, in the example illustrated, of 
greater diameter than the said tube, with 
the object that the said tube 1, shall not 
come into' contact to any material extent 
with the walls of the opening formed by 
driving the preparatory pile, so that the 
said pile can be driven without the exces- 
sive friction which results from the contact 
of the earth with the sides of the pile, when 



the pile, as a whole, is cylindrical or of the 
same width throughout, or tapers from top 
to bottom, the improved pile being also 
capable of easy withdrawal, owing to the 
fact that the point or end-piece 3, remains 
at the bottom of the opening, and the tube 1 
is free from any material contact with the 
walls of the opening above the said point or 
end-piece. 

After the said preparatory pile has been 
driven to the proper depth, the concrete or 
cement is passed into its interior, and when 
a sufficient quantity has accumulated at the 
bottom of the tube above the point, the tube 
is withdrawn, either slowly and continu- 
ously or intermittently — a little at a time, 
and, during such withdrawal, the supply of 
concrete or cement to the interior of the 
tube is effected intermittently, so that the 
conrrete or cement will escape into the open- 
ing above the point 3, as shown in Figs. 2. 
3 and 4. until by the time the tube 1 is 
completely withdrawn, the opening will be 
filled with conrrete or cement. 

When the opening is formed in wet 
ground or beneath water, the concrete or 
cement is introduced into the tube or hollow 
stem at such a rate as to always maintain 
a head of concrete nr cement at the I 
thereof so that water cannot gain ac< 1 



* Reported by DOUGLAS I.f.echman, A.I.M.E. Barristcr-at Law 
** Official indication cf the two amendments. 



'•- 



LAW REPORT. 



1C3NCRETFJ 




188 



(C CCSM5TE0CT10NAIJ 



LAW REPORT. 



the interior <i f the tube, but will be dis- 
placed upwardly as the concrete or cement 
escapes from the lower end of the tube and 
into the opening outside the tube. 

By this means caving-in of the walls of 
the opening, when such opening is formed 
in unstable ground, is effectually prevented, 
and the concrete or cement pile, when it 
becomes (set, is a homogeneous structure 
possessing the needed strength. 

The point 3 can be made of any desired 
shape and of any material which will with- 
stand the shock of driving, preference 
being given to a point of concrete which 
may, if desired, be sheathed with sheet 
metal, except at the top, or be internally 
reinforced to strengthen it, as the plastic 
concrete or cement of which the pile is 
composed will take a better hold upon such 
concrete point than upon a metal or other 
point not alTording so good a holding sur- 
face. 

Although the invention is described in 
connection with a preparatory pile provided 



with a cap and a detachable point, the 
method of forming concrete or cement piles 
may be employed in connection with the 
use of any suitable hollow preparatory pile 
open at the bottom for the escape of the 
concrete or cement therefrom as the 
preparatory pile is withdrawn, but is limited 
to cases in which the hole made by the 
preparatory pile is of larger diameter than 
that of the greater part of the tube or stem 
of the pile. 

Claim, — The method of forming con- 
crete, or cement {sic) piles, which consists in 
providing a hollow pile with an enlarged 
and detachable point or end-piece, of con- 
crete or other material, or materials, sinking 
the said pile into the ground to form a hole 
larger than the pile stem, then slowly, or 
intermittently withdrawing the said pile 
without its said point or end-piece, and 
filling the hole above the said point or end 
piece with concrete, or cement during such 
withdrawal, and then permitting the con- 
crete, or cement to set, substantially as here- 
inbefore explained. 



The essential characteristic of the invention, therefore, is the making of the shoe 
of larger diameter than the tube; in practice it is made about 1 in. larger. 

For a time the Defendants were licensees under the Patent, but now the Plaintiffs 
act as contractors themselves. In their defence Messrs. Stewart relied partly upon 
Potter's early patent and partly on a tubular well which had been sunk with a pointed 
bottom and perforated lower ends. In the course of the work a large tube had been 
driven down and gravel, etc., extruded from it to form a filtering material. 

In the result, Mr. Justice Neville held that there was sufficient subject matter to 
support the patent, and that the Defendants had infringed. Accordingly he ^ave 
judgment for the Plaintiffs, granting them the usual relief, including an injunction 
against the infringement of the Letters Patent, damages and costs. By the consent of 
the Plaintiffs the injunction was suspended in respect of contracts already accepted by 
the Defendants provided notice of appeal was given within fourteen days. 



,S\, 



B. I. WELLER. 



[CONCRETE] 




CONCRETE 

GRAIN 
ELEVATORS 

IN 
CANADA 



By B. I. WELLER. 

The Ninth Convention of the National Association of Cement Users took place in 
December last, and quite a number of interesting papers ivere again read, of "which ive 
reprint the following one in abstract form. Further papers tvill be printed in subsequent 
issues. — ED. 

EARLY HISTORY OF GRAIN ELEVATORS. 

Elevators as a means of housing and handling grain did not make their appearance 
until the latter part of the last century. The lirst real elevator of which there is any 
record is the " cribbed " wood type, and there are still a good manv of these houses in 
existence. This old type is interesting when it is considered that at one time an 
elevator of nearly four million bushels capacity was erected complete, and almost 
totally filled with grain, in a period of forty-four days. Of course, lumber was plentiful, 
and no expense was spared and no restrictions put on the builder except to gain time. 
As the price of lumber advanced, it became necessary to cast about for other kinds of 
material with which to build, the elevator operator and owner seeking for a material 
which would appreciably lower the insurance rate, which was very high on wood. 

The first fire-resisting elevators were built of steel, practically on the same plan as 
the old wooden structures, which were rectangular in plan and had cribbed bins elevated 
on posts and usually arranged to suit unloading conditions. Up to this point all storage 
and handling devices were carried under one roof, but it was then demonstrated that 
all machinery for unloading, handling, and shipping could be more economicallv 
installed in separate buildings called the working house. This was accomplished bv 
having two or more parallel tracks alongside of the house for unloading, thus shorten- 
ing the house and necessarily making it more economical ; a separate building for 
storage being erected having larger compartments than in the working house. At 
ab.ait this time there came into common use, in the construction of elevators, brick, 
tile, and concrete, which will be dealt with later. 

CLASSIFICATION OF GRAIN F LEVATORS. 

Grain elevators in general may be classified under the following heads : Terminal. 
Transfer, Country or Line Houses, Private or Hospital. Of the above-named classes 
the Terminal is by far the largest. This type of house is to a greater or less extent 

under the supervision of the Government, both as regards the classification of the 

different kinds of grain and also the weights of same. 

Terminal houses are so called because they are usually situated en a lake . r ocean 
I -1 ''' and receive their grain either direct from the farmer or through their line or 
country houses. 
190 



f a. CONSTRUCTlONAJ-1 



CONCRETE GRAIN ELEVATORS. 



When grain is received by ;t terminal house ii i> given a grade by the inspi 
and either stored awaiting future delivery or is shipped direel b) boal or rail, usually 
tin farmer. Part of this grain may have to go through different processes, -> 
bleaching, drying, or cleaning. The cleaning ,-111(1 drying when necessary, of certain 
portions of this grain, is generally absorbed by the operators of the house. 

Terminal houses are usually controlled by grain firms, who also have tin i r own 
line ami country houses. These country houses vary in size from 10,000- to 50,000- 
bushel storage capacity, and are placed along railroads throughout the country where 
tli< grain is grown. These houses, atter receiving the grain from the farmer, ship 
direct to their terminal house. 

METHOD OF HANDLING GRAIN. 

It may be interesting to give an idea of how much wcrk can be done by some of 
the elevators which have lately been constructed. The Canadian Stewart Company 




Terminal Elevator, Fort William, Ontario, for the Grand Trlnk Pacific Railway. 



recently constructed a reinforced concrete elevator for the Grand Trunk Pacific Railroad 
Company, at Fort William, Ontario. In the track-shed of this elevator there is room 
for spouting over the r< ceiving pits, twenty cars at one time, and in a double shift of 
twenty hours it is possible to unload ewer 600 cars of grain. A boat which can carry 
a cargo of 400,000 bushels of wheat can be loaded at this elevator by means of five 
dock spouts in about three aril a-half hours. This house is equipped with nineteen 
cleaning machines, each one able to clean as high as 3,000 bushels per hour, and in 
the dryer house it is possible to dry about 2,000 bushels per hour. There are also 
nineteen elevator legs in this house. Most of these le^s have a capacity of elevating 
[8,000 bushels per hour each. There are ten 2,000-bushel hopper scales, ami it is 
interesting to note that each hopper can be filled, weighed, and unloaded in a Iittl 
than three and a half-minuies. The total capacity of this house is a little less than 
three and three-quarter million bushels, of which the working house capacity is about 
three-quarters of a million bushels storage capacity. 

In regard to power for these elevators, it may be aid that, almost with 
tion, all up-to-date houses are now equipped with individual motors for the differenl 

191 



B. I. WELLER. 



[CONCRET E) 



machines, conveyor belts, etc. This has been proved more satisfactory as to service 
and also is more economical. 

Rubber belting of a high grade is used both for conveyors and elevator legs, and 
in transmission manilla rope is used, both gears and belting having become obsolete, 
the former principally on account of the noise and the latter on account of slippage. 

In regard to marine towers, the above-mentioned firm recently erected for the 
Washburn-Crosby Company, of Buffalo, a tower which was cylindrical in form and 
160 ft. in height. This tower was equipped with marine leg, which is by far the fastest 
en the great lakes, being able to unload a complete cargo of grain at an average speed 
of 22,000 bushels per hour. The tower, of course, also contains automatic scales, and 
delivers the grain direct to the company elevator by means of conveyor belt running 
through a tunnel. 

MATERIALS USED IN CONSTRUCTION. 

The different materials from which elevators have been built are as follows : Wood, 




Interior View. 
Terminal Grain Elevator, Fort William, Ontario. 

steel, brick, tile, and concrete. These have been named in the order in which they 
came into general use, and at the present time few elevators are built of any material 
save concrete. Wood was found to be very expensive when insurance rates were taken 
into consideration. Steel is a high conductor of heat, and there is on record an instance 
where four box cars, lying in a track-shed, caught fire, resulting in the wrecking of 
a steel house of over one-half million bushels capacity. The steel walls of the storage 
tanks were, of course, very thin, offering little resistance to fires due to the burning of 
adjacent buildings, and so much of the grain would be damaged due to excessive heat 
thai steel has been found impracticable. 

There have been a great many elevators constructed of brick, but it is usually too 
costly on account of the walls having to be made so thick in order to suit reinforcing 
conditions, etc. 

Tile was used for a number of years, and even now and then elevators are built of 
this material. The main fault to be found with this material is that it is hard to ensure 
an absolutely waterproof job. 
192 



&O0N5TBUCTIONA 
EMGIMEE.R1NG 



a 



CONCRETE GRAIN ELEVATORS. 



The first concrete elevator was built in 1902, and as soon as the tanks had bden 
tilled with grain several of them burst. This naturally retarded the use of concrete for 
t^vo or three years. However, after one or two concrete elevators had been erected by 
well-known firms, the elevator owners regained confidence in this material. For some 
time concrete was used only in foundations and in the storage annexe, steel or 
being used throughout the working house. Later on storage bins in the working house 
and the columns supporting same were made of concrete, and only the cupola, which 
is that part of the elevator above the tanks, was built of steel. 

It has been clearlv demonstrated that there is no better material for protecting the 
strain than concrete, on account of its being a poor conductor of heat or cold, and, 
being denser and freer from porosity than either tile or brick, it has greater water- 
proof qualities. 




Terminal Elevator, Fort William, Ontario, for the Grand Trunk Pacific Railway. 
Another point in favour of concrete construction is the low cost, due to the fact 
that there is practically no skilled labour required in the construction of the modern 

elevator. 

METHODS OF CONSTRUCTION. 

The equipment for handling concrete in the modern elevator differs very little from 
the methods used in placing concrete in any other building, with the exception of the 
forms, in which great advancement has been made in the last few years, the forms for 
the foundation, of course, being stationary, but all forms above the foundations are 
movable. These forms are made of 2-in. plank, surfaced on one side and two edges, 
and the form over all is about 4 ft. 6 in. in height. After the foundation has been 
completed these forms are set over the whole area and filled with concrete in layer 
about 8 in. thickness. The raising of these forms is accomplished by a series of jac 
in which there are from six to eight on each tank, or, if they are used on straight walls, 
they are placed about 5 or ft. apart. These jacks are set in a yoke which is a frame- 
work of steel and is connected to the wooden forms. Through each jack there i 
jacking rod about 1 in. in diameter running vertically. To operate th 
placed in the socket, causing a screw to turn which, if turned to the 1 
forms, and if turned to the left, the jack itself climbs the jacking rod, whi 

•93 



B. I. WELLER. 



[CONCRETE] 



r< main stationary, being supported bv the two adjacent jacks. By reason of the rod 
passing through the jack, the load is applied concentrically, and leaves no tendency 
for the forms to bind. These jacking rods are placed directly on the top of each other, 
and no dismantling of the forms is required when additional rods are added. These 
yokes are connected by means of trusses, and these, in turn, support the temporary 
floor for the convenience of the working men and permit easier handling of material. 
This continual moving of forms does away with the horizontal rings and discolora- 
tions so often to be seen in the first concrete elevators. This type of form also has 
greatly reduced the cost over the stationary forms used originally or the primitive 
jacking system first adopted, which was accomplished by jacking from the ground all 
the way to the top of the elevator. 

In the working house the girders, where required for floors, are poured simultane- 
ously with the walls, the floor slab generally being put in later. This is done so as 
not to impede the progress of the wall forms. In reinforcing the tanks flat bars are 
used, being placed midway between the forms and at equal intervals, the difference in 
piessure below and above being taken care of by the size of the flat. The jacking rod 
:>n which the forms are raised is also part of the vertical reinforcing, and similar rods 
plac< d between the series of jacking rods form the balance of the vertical reinforcing. 
The tanks are always laid out in parallel rows. Contacts must be provided for, and 
this is generally arranged by a system of horizontal anchors and additional concrete in 
the interstices. This arrangement of bins leaves the space between the different tanks, 
which is called an interstice bin. 

As the elevator is usually placed on the water front, and as its elevator boot tanks 
and receiving pits are necessarily some distance below grade, there is generally water- 
proofing to be taken into account. This is usually accomplished by means of the 
membrane system of waterproofing. 

In regard to the balance of the construction, it is so nearly allied to other branches 
o reinforced concrete building that it is needless to go into further details. 

In conclusion, it is fair to add that the modern elevator has been and will continue 
to be a great factor in the upbuilding of north-west and also western Canada, and, in 
conjunction with the railroads, the elevator has been responsible for the steady crop 
increase, until it is safe to predict that in the next half decade, the wheat crop of 
Canada alone will exceed 500,000,000 bushels per annum. 




Terminal Elevator, Fori William, Ontario, for the Grand Trunk Pacific Railway. 



194 



f"j, C'ONM"l?l!<.TIONAl!) 
[A ENGINEERING — J 



CONCRETE IN ITS LEGAL ASPECT; 




"^rr 



RECENT VIEWS ON 
CONCRETE AND REIN. 
FORCED CONCRETE. l 



THE CONCRETE INSTITUTE. 



It is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available for reference purposes. 

The method ive are adopting, of dividing the subjects into sections, is, ive believe, a 
nev) departure. — ED. 

THE CONCRETE INSTITUTE. 

CONCRETE IN ITS LEGAL ASPECT. 

By W. VALENTINE BALL. 

The following is a>i abstract of a Paper which was read at the Ordinary General 
Meeting of the Institute on January gth, iqij. 

PRELIMINARY. 

In his opening remarks the author pointed out that there wore certain difficulties 
in the presentation of this paper. There is no statute law which is specially applicable 
to the subject in hand, and of reported cases relating specially to concrete there are 
none. Nevertheless, there are certain aspects of the law relating to building and 
engineering contracts which may be of interest to members of the Institute. There 
are a few considerations which may properly be kept in view by the parties to a con- 
tract which involves the use of concrete or reinforced concrete. 

In the course of the paper the term " employer" is to stand for the local authority, 
company, or person who requires the work to be carried out. The term " contractor " 
will signify the firm of contractors or builders employed directly by the employer, while 
the term " sub-contractor " will include any firm or company which is cmploVed to 
carry out some portion of the work under a sub-contract. 

GENERAL OBSERVATIONS ON THE EMPLOYMENT OF A SUB-CONTRACTOR. 

In carrying out a large contract the employment of sub-contractors or specialists 
is very common; indeed, the employment of sub-contractors is almost inevitable when 
the work in hand is of any magnitude. 

Generally speaking, where there is no stipulation against sub-contracting a con- 
tractor may employ sub-contractors. The rule is, however, subject to the qualification 
that it does not apply when the employer reasonably and naturally looks for the 
personal service and attention of the contractor. Thus, if the work in hand were of 
a highly special character, it would not be competent for the contractor who was skilled 
in that class of work to hand over its performance to some one else. 

The following clause may be inserted if it is desired to ensure that the contractor 
shall carry out all the work himself : — 

"This contract is and shall he considered as a personal contract by the conti 
himself, who shall personally, with the assistance of skilled fort nun, agents, mechanics, 
and workmen, direct and execute the works." 

The more approved practice, however, is to leave it to the engineer to say whether 
and how far sub-contrai tors may he employed. The following clause, which is to he 
found in the model conditions approval by the Institute of Electrical Engineers, may 
safely be used : — 

"The contractor shall not, without the consent in writing of the engin< 
his contract, or any substantial part thereof, nor under-let the same, or 



THE CONCRETE INSTITUTE. [CONCRET E 



part thereof, nor make any sub-contract with any person or persons for the execution of 

any portion of the works, other than for raw materials, for minor details, or for any part 

of the whole of which the makers are named in the contract." 

Another form of clause prevents the contractor from making a sub-contract with 
any workman or workmen for the execution of any portion of the work, except with 
the consent of the engineer. It also provides that if the contractor shall sub-let or let 
at task work any portion of the work he shall in such case forfeit to the employer the 
sum of _£.ioo as liquidated damages. 

WHO IS LIABLE TO PAY THE SUB-CONTRACTOR ? 

A most important question from the point of view of the sub-contractor is, Who 
is liable to pay him ? He naturally wants to be sure that his labour will not be in vain. 
Generally speaking, the employer is not liable to a sub-contractor, unless an agreement 
between them can be proved. Such an agreement will not be implied from the mere 
acceptance of the sub-contractor's work. For instance, where an employer contracted 
with a builder to do certain work on his house, and a tradesman supplied goods to the 
builder for use en the house, it was held that the employer was not liable for their 
price (see the case of Brahmah v. Abingdon, cited in Paterson v. Gandasequi, 1S12, 
15 East. 62). The employer does, however, become liable if it can be shown that there 
is a contract between him and the sub-contractor. 

An employer may also become liable to a sub-contractor by going surety for him. 
in that case, however, there must be something in writing, as a contract of guarantv 
cannot be sued on unless it is in writing. But there is a difference between a promise 
to pay the debt of another and a direct promise to be liable oneself in any event. In 
the latter case a written contract need not be proved. Thus, if the employer promises 
to pay the sub-contractor out of monies which he has to pay to the head contractor, 
this would be treated as a direct promise to pay (Dixon v. Hatfield, 1S25, 2 Bing. 410). 

There is another way in which the employer may become directlv liable to a sub- 
contractor. It may be proved that the head contractor, in employing the sub-contractor, 
really acted as the agent for the employer. The onus of proving this will be on the 
sub-contractor (see Woodward v. Buchanan, 1870, L.R. 5 Q.B. 285). 

The question, Who is the sub-contractor to look to for his remuneration? therefore 
turns upon the conditions of his employment. 

The question of liability largely depends upon whether the contractor was con- 
stituted the agent of the employer to employ the sub-contractor or to purchase goods 
from him, and to establish privity of contract between the employer and such sub- 
contractor. Where the defendant (a building-owner) entered into a contract with a 
builder by which the latter agreed to build a house for him under the supervision of 
an architect, the contract provided that the provisional sums for goods to be ordered 
from special artists or tradesmen should, as the architect should certify, be payable 
by the builder or the building owner. 

WHERE THE CONTRACTOR BECOMES INSOLVENT. 
Trouble frequently arises in cases where, owing to the insolvency of the builder, 
the sub-contractor is compelled to look to the building-owner. He often makes such a 
claim without avail ; but by means of a special clause this difficulty may be obviated. 

HOW FAR THE CONTRACTOR IS LIABLE FOR THE DELAY OF THE 

SUB-CONTRACTOR. 

If an employer reserves to himself the right of employing specialists to do anv 
portion of the work on a large contract, he does not thereby give any implied under- 
taking to the h<ad contractor that he will be responsible for any damage caused to the 
builder by any delay or default on the part of the specialists. 

As a general rule, however, the sub-contract contains a clause to the sffecl that 
■' the sub-contractor shall pay to the contractor a certain sum as liquidated damages, 
and not by way of penalty, per day for each day after the day of 

that the work shall not be finished or complete, and it shall be lawful for the said 
contractor to retain the said sums out of any money payable to the sub-contractor." 

LIABILITY OF THE SUB-CONTRACTOR FOR DELAY. 

The liability of a sub-contractor for delay in completing the work lie has under- 
taken to carry < ut depends <>n the terms of his contract with the head contractor. If 

196 



A'glrjNEEBi'No^ CONCRETE IN ITS LEGAL ASPECT. 



hi does not know thai the head contractor has undertaken to do the work within a 
specified time he will not be liable for the damages claimed and recovered by th<: em- 
ployer for delay; but it is otherwise if it is shown that he knew what would be the 
consequences of delay. To quote the case of 'The Hydraulic Engineering I 
McHaffie, 1878, 4 Q.B.D. 670, the plaintiff company contracted with an employer to 
make a pile-driving machine. The defendant was employed to make a pari ..1 the 
machine and to deliver the same bj the end of August, when, as he knew, the plaintiff 
company had to make delivery to the employer. The defendant was a month late in 
making delivery of his part, with the result that the employer refused to accept the 
whole machine. As it was of peculiar construction no market could be found for it, 
and it was therefore sold as old iron. It was held that the plaintiffs were entitled t<i 
recover the profits which they would have made on the sale to the employer and the 
expenditure thrown away on the other parts of the machine. From this it may hi' 
inferred that any sub-contractor far the execution of a portion of a contract for large 
works may find himself cast in very considerable damages if he is guilty of delav. 

USE OF MATERIAL ON THE SITE. 

It may well be that in some cases the builder or other person who has to provide 
concrete will find a large bed of gravel or other useful material on the site. How far 
can he use it in the fulfilment of his contract? 

An obligation upon a contractor to clear away old materials does not necessarily 
vest those materials in him. Again, where a contractor is bound by his contract to 
excavate, the materials excavated do not necessarily vest in him. On the contrary, if a 
contractor make use of materials supplied to him the employer may set off their price 
against the amount due under the contract. For instance, in one case the plaintiff 
contracted to do certain work for the defendant and to find the materials. The defendant 
supplied part of the materials which the plaintiff made use of in the work. It was 
held that the defendant was entitled to deduct the value of the materials supplied by 
him from the contract price (Newton v. Forster, 1844, 12 M. and W. 772). 

The importance to the employer of some clause dealing with old materials lies in 
the fact that if nothing is said about them the contractor may remove them. Having 
removed them he may sell them. In that case, if he were to become bankrupt, the 
employer could not get the goods back, but would be relegated to his right of proving 
for their value in the contractor's bankruptcy. 

Where the contract for erecting a building or executing other works makes no 
reference to old materials, it seems that the contractor will be under an implied obliga- 
tion to clear them away. There is no English case directly in point, but the principle 
has been laid down in several American cases. 

IMPORTANCE OF PROVIDING FOR THE REMOVAL OF OLD MATERIALS. 

It is well for every contractor who has undertaken works which involve the 
clearance of a site to take care that he is adequately protected. The removal of a 
large mass of concrete would be a long and costly operation, while to remove reinforced 
concrete, knit together with ribs of steel, is the labour of Titans. When the time 
arrives for the removal of modern buildings it is clear that the contractor must needs 
regard clearances as a very important item when considering the amount of his 
tender. 

EXPRESS PROVISION FOR MATERIALS ON SITE. 

In drawing his specification the architect often inserts a clause to the following 
effect, " Materials on the site to be used as far as possible." If a tender is made by 
a contractor on the basis of such a specification the architect should take care to 
ascertain whether the contractor has made any deduction in respect of old materials. 
If the contractor, having made m> deduction, uses any of the materials the architeel 
may set their value off against the contract price; and even if the contractor has 
made a deduction, but has not informed the architect of the fact, there may - 
a set-off. 

CLAUSE TO PROVIDE FOR THE USE OF OLD MATERIALS. 
The following is a convenient form of clause : — 

" All materials upon the site or upon the space to he covered by the ! 
contiact works! at the date of the contract, and all materials and things e: 

197 



THE CONCRETE INSTITUTE. [CONCRETE] 

contractor from the work-, shall remain the property of the employer until paid for by 
the contractor. Such of them as shall be approved by the .architect for the purpose of the 
works shall be paid for by the contractor at a price to be named in his tender or, if not 
named, to be ascertained by the architect, and all other materials shall be removed by the 
contractor from or deposited, stacked, or spread en the site as, where and when directed 
by the architect." 

This clause may properly be inserted in a contract which involves the making of 
concrete, because it i> necessary that gravel, etc., to be used should be approved by 
the architect. 

PROVISION FOR WATER. 
Another question of importance is the provision of an adequate supply of water. 
When- iN n is a good supply at hand in the mains no difficulty need arise. The 
question will simply be, Is the employer or the contractor to pay the water rate during 
the work of construction? But if there is no municipal or other supply the difficulty 
may have to be met by sinking a well or pumping from a lake or river. Suitable 
clause.-, must be inserted in the contract to place the burden of pumping or well-sinking 
on the right shoulders. 

RIGHT TO REJECT MATERIALS. 
It is important to consider the question whether the architect has the right to 
reject improper materials when brought on to the works. In this regard the provisions 
of the R.I.B.A. fo/m appear to be fairly satisfactory. 

SUPERVISION WHEN CONCRETE BEING LAID 
Concrete is a matter which may require some supervision on the part of the 
architect. To cover up wet concrete may involve serious disaster, and it seems that, 
in the conduct of ordinary building operations, it is the duty of the architect to attend 
tu this matter; although in some respects he is an arbitrator, he is also a servant to 
the building-owner or employi r. 

" There may, of course, be manv things which the architect cannot be expected 
to observe whilst they are being done — minute matters that nothing but daily or even 

hourly watching could keep a check upon But he, or someone representing 

htm, should undoubtedly see to the principal parts of the work before they are hid 
from view, and if need be he should require a contractor to give notice before an 
operation is to be done which will prevent his so inspecting an important part of the 
work as to be able to give his certificate upon knowledge, and not on assumption, as 
to how work hidden from view has been done." 

So much for the liability of the architect. In a case where there is no architect 
employed the problem assumes a somewhat simpler aspect. The builder then acts as 
skilled adviser, as designer, and as superintendent of the building. 

DEFECTS AFTER COMPLETION. 

The author stated he had not sufficient technical knowledge to know whether con- 
crete or reinforced concrete is liable through the mere lapse of time to deteriorate. 
Take, for instance, the case of a concrete archway. Suppose that it develops .a crack 
within six months of the date of completion, anil the contract is silent on the question 
<>f liability — what is the legal position? The mere fact that the employer has accepted 
the bridge aid paid for it would not amount to a waiver of his right to damages if the 
bridge failed through some fault for which the contractor was responsible. 

F< r instance, in one case the plaintiff, a shipowner, bought copper sheathing of 
the defendant, a copper manufacturer, and the copper was put on the ship., which 
sailed; but the copper, instead i>f lasting four or five years, as usual, corrod d in four 
or five moniths and became unlit. It was held that the n'aintil't could recover damage -. 
notwithstanding the acceptance (Junes v. Bright, {829, ,s Bing. 533). 

Further, payment of, or judgment for, the contract price is no bar to claim by 
the employer for defective work, nor for damages arising ouil of the breach (Davis ;■. 
I b dges, 1871, L.R. (> Q.B. 687). 

ADVANTAGE OF HAVING A TIME LIMIT TO LIABILITY FOR DEFECTS. 

From the poinl of view of the contractor who has in put in concrete, it is besl to 

put a definite period to his liability by an <-.\press clause in the contract, because where 

work is agreed to be done to the approval of the employer or his architect, the expres- 

198 ' 



EBBBI&sl CONCRETE IN ITS LEGAL ASPECT 

sion <»f thai approval will prevent any recoverj by him for patent defects subseauen/tlv 

discovered. y 

Where the contract is sileml in the matter, the measure of damages for mcompl te 

or defective performance is what it would cosl to rectify the defects or omissions at the 

(Lite when they might have been discovered, or when the particular part of the work 

was completed. 

Apart from the terms of the contract, it is manifest that the contractor could not 
by any possibility be held responsible for defects arising in the course of time from wear 
and tear. But if there is a structural defect which ought to have been detected and 
put right when the works were in hand, it is conceived that the contractor remains 
liable for that. 

UNFORESEEN DIFFICULTIES IN CARRYING OUT THE WORK. 

There is one matter to which the contractor who has made himself responsible for 
the laying of a large bed of concrete must pay particular attention. The employer will 
endeavour to put upon the contractor the entire responsibility for the site — the nature 
of the strata to be met with when making excavations and their capacity to support 
the intended structure; and he will also seek to put upon the contractor the responsi- 
bility of estimating how much material will be necessary to complete the work. 

It is a well-established principle of law that in the performance of an ordinary 
building agreement or other contract for works, the risk of possibility of performance 
is on the contractor. (Thorn v. Mayor of London, 1876, L.R. 1 A.C. 120.) 

The principle of Thorn v. Mayor of London was long applied to excuse employers 
in cases of a similar kind; but a more recent case has shown that the disclaiming 
clause will not necessarily relieve the employer. If he puts forward plans, etc., as 
showing ihe nature and extent of the work, he may be held liable if those plans were 
false to his knowledge or were put forward recklessly without proper inquiry as to 
whether they were true or false. 

CLAUSES DEALING WITH CEMENT. 

Certain points seem to require attention in contracts relating to the supply of 
ci ment. Thus, provision must be made for testing by a person responsible to the 
employer, and for suitable accommodation in a dry place. In the case of a very large 
contract it may be necessary to erect a special building for the storage of cement until 
it is required for use. In that case it will be necessary to specify who is to erect the 
building. 

CONCLUSION. 

In concluding, the author remarked that after his paper had appeared in print, 
he had received a copy of Messrs. Scott-Fraser's specification of reinforced concrete 
which was published in 1911, and contained some general and preliminary clauses. 
This specification, the author remarked, appeared to be drawn in a form which might 
be usefully adopted by those who have to carry out this kind of work. 

Before opening the discussion the President read a letter from Mr. Percy Waldram, F.S.I.. 

M.C.I. 

Extract from Mr. Waldram , s Letter. 

" Mr. Ball's interesting and valuable paper would appear to have omitted one point, 
which might possibly be of the greatest possible importance, viz : 

"Who is responsible in the event of failures due to over-daring design? 

" In many cases where reinforced concrete is used the engineer or architect is not in a 
position to check the calculations. lie employs a specialist firm to design and calculate the 
work, receives from them a price, and instructs the general contractor to give them the order. 
The latter merely carries out that instruction. In due course the specialist firm send on to the 
work, not their own workmen, but the workmen of a second sub-contractor employed by them. 
In the case of a public contract not long ago. the Local Government Board Inspector asked who 
would be responsible for the accuracy of the calculations. The prospective contractor was in 
this case a licensee of the specialists' system He promptly disclaimed responsibility for 
calculations which he had never seen, and could not follow if he had. The local engineer 
said the same, whilst the specialists replied that they were employed to design only, and that 
if they designed in accordance with ordinary practice- their responsibility was at an end; they 
were not parties to the contract, and had no more responsibility than the local engineer. 

" Probably all three were perfectly correct, but the members of the local Council were not 
impressed. 

E 199 



THE CONCRETE INSTITUTE. [CONCRETE] 

"It is not always easy to get proper calculations. 

" Still more difficult would be the case where a failure occurred with regard to some 
of the matters upon which we are still somewhat hazy. Even the R.I.B.A. Reports and the 
proposed L.C.C. Regulations are almost entirely silent with regard to double reinforced 
beams. 

" Possibly Mr. Ball could suggest some form of undertaking which would fix the responsi- 
bility for reinforced concrete work upon the shoulders of the specialist firms who design it, 
and upon their sub-contractors who carry it out, and also state whether that undertaking could 
be a joint and several one, and for how long it would operate in the event of no time limit 

being stated." 

DISCUSSION. 

Mr. A. Albaa H. Scott, M.S. A. (Member of Council C.I.), said Mr. Waldram's letter raised 

some of the most important points that can be raised with regard to reinforced concrete work. 

The usual custom in building contracts has been, and is being, unfortunately entirely departed 

from in reinforced concrete work. 

He said there were five methods specially in vogue at the present time where the reinforced 
concrete specialist came in, and, after dealing with them in detail, said that with the various 
cases quoted as to sub-contractors it is placing both the architect, and eventually the building 
owner, from a financial point of view, in a most extraordinary position, because he at least, 
as a layman, has no idea where he stands at all. 

The only thing that would appear to cover him is the usual clause in the R.I.B.A. form 
with regard to sub-letting, which is a very short and concise clause. It simply says that the 
contractor shall not sub-let without the architect's written sanction. 

So far as the builder and the sub-contTactor are concerned with regard to penalties, the 
Master Builders' Association have a sub-contractors' form which is based on the R.I.B.A. 
form, and it there gives in the form of a schedule the whole of the main contract so far as it 
applies to the sub-contractor, and the sub-contractor has a right to inspect the main contract. 
It is a very good contract. 

In the course of the paper it is stated that the architect should require a contractor to 
give notice before an operation is to be done ; it will prevent his inspecting the important part 
of the work, in giving a certificate on knowledge and not upon estimation. In reinforced 
concrete work, unfortunately, every part of the work is hidden which is of importance, and 
even if an architect spent the whole of his time on the job he would have to have a dozen 
pair of eyes and a dozen personalities on a fair-sized job. 

Mr. W. Q. Perkins (District Surveyor for Holborn ; Member of Council C.I.) : In the 
early part of the paper it is stated there is no statute law which is specially applicable to the 
subject in hand. There are the London Building Acts proposed regulations which would 
govern reinforced concrete, and the bye-laws governing concrete in foundations in London, 
in foundations outside of London, and the construction of walls in London. 

Looking at the paper from the official point of view, it would be very interesting if the 
author would express his views as to the contractor's position with regard to this Building Act 
and the bye-laws just mentioned. Many instances similar to the following one have come to 
his notice. The specification furnished by the architect described certain concrete for a wall 
to be composed of one part of cement to six parts of aggregate. The bye-law requires concrete 
for the work in question to be one part of cement, two parts of sand and three parts of 
aggregate, and the local authority (the speaker in this case) insisted upon the work being done 
accordingly. One of the conditions of the contract stated that the whole of the work was to 
be in accordance with the bye-laws, and to the satisfaction of the local authority. In such a 
case, can the builder, having regard to this clause, claim an extra payment for the additional 
amount of cement used, for the sand, and for the extra labour in mixing the concrete when 
composed in accordance with the bye-law? — that is to say, he has to handle three materials 
instead of two. 

Mr. Fiaader Etchells quoted a number of Building Acts and Bye-laws where concrete or 
reinforced concrete are mentioned in an ambiguous way. 

Mr. Osborne C Hills, F. R.I.B.A., Member of Council C.I. (District Surveyor for tin- 
Strand) asked the Lecturer what he thought was the position to-day of the architect who 
specifies reinforced concrete floors he cannot supervise. There was the case of a floor not a 
mile away from the meeting place with a certain amount of steel work. The proper amount of 
steel work was provided for. At the end of the job a certain amount of steel was carted 
away, and it was not known how the surplus was come by. After some searching it was 
discovered at last that there is a whole bay of concrete, a 17- ft. span, and not one iota of 
the steel rests there. Is tin- architect responsible lor that? Now it has been discovered, it is 
200 



[&ewi>!ee^w^ CONCRETE IN ITS LEGAL ASPECT. 

going to be put right ; but, had it not been discovered and an accident h ure]> 

the architect would not be responsible for it? 

Mr. Herbert Shepherd, A. R.I.B.A., M.C.I. , said he did not agree with Mr. Etchells or 

Mr. Hills. If they looked back to the 'fifties they will see that at that time concret 
being advertised and was being dealt with then in a very large way all over the country as 
the "new material." They were actually building concrete houses in the North of England 
at that time. The 1855 Act originated out of a request to the Government of the day by the 
Royal Institute of British Architects to assist them in reforming what was then called "The 
Metropolitan Building Act," and it was with their assistance principally, and with the aid 
of the Royal Institute, that those draft regulations were first brought into being. And the 
interesting part is this, that the very first lecture that was ever given, and the very first prize 
that was ever given by the Royal Institute of British Architects, was in 1834, f° r a paper on 
concrete. 

It seemed an anomaly to him that even at the present day, in spite of the revisions which 
the Building Acts have received from the progress of construction, he believed it is still possible 
that one can legally put g inches of concrete under a wall 80 ft. high. 
MR. VALENTINE BALL'S REPLY. 

Mr. Valentine Ball, replying to the points raised by Mr. Scott, said, in the case of the 
specialist employed by the architect, he thought with regard to the liability of the contractor 
for the specialist, that had been to some extent foreseen in the R.I.B.A. Form, Clause 20, 
where it will be found that the contractor is entitled to object to the employment of any 
specialist who will not enter into a contract with him indemnifying him from the consequences 
of the specialist's fault and delay ; and that, he supposed, in some measure afforded protection 
to the contractor. 

But as to the general question, who is liable for a fault in design, the decisions on the 
point appear to show that if the employer engages a contractor to use a particular kind of 
patent roofing, and stipulated no other should be used, and the patent roofing turned out to 
be wholly incapable of keeping out the wet, then the responsibility is not upon the con- 
tractor. He simply did what he was told ; but as to the exact position where the designs of 
the engineer, as worked out by the specialist, are faulty, then again, he supposed, the liability 
would be on the engineer or the architect. 

With regard to the question of the inspection of reinforced concrete by the architect when 
it is in the lay, it appeared to him that the modern class of building contract does not provide 
exactly what the duties of the architect shall be, and it seemed utterly unreasonable to 
suppose that the architect must be there when every piece of steel is being put into place, 
or that any Court of Justice would hold that that was the duty of the architect. He could 
perhaps protect himself by insisting that more than one cleTk of the works shall be employed, 
and that the clerk of the works shall be careful to exercise due diligence in supervising the 
contractor. 

Answering the interesting question raised by Mr. Perkins with regard to the observance of 
by-laws by the builder, the R.I.B.A. Form expressly provides for that by Clause 5, where the 
duty of complying with by-laws past, present and future is thrown upon the builder. If 
he finds, in carrying out the work, that he cannot comply with the by-law by complying with 
the specifications, he was entitled to give notice to the architect and say he must comply with 
the by-law, and if ha complied with the by-law, he would be entitled to treat everything — 
all the expenses which he so incurred — as an extra under the contract, in accordance with 
Clause 13 of the FoTm, just as other extras are dealt with. In the very recent case of John 
Barker and Co. against the Hurlingham Club, where the whole question of extras was gone 
into, and, notwithstanding the opinion of the architect, the builder was entitled to treat 
compliance with by-laws as an extra, an omission. 

In conclusion, the lecturer promised to give written replies to several other questions 
which might be raised. 

THE INSTITUTION OF CIVIL ENGINEERS. 

THE CANTON . KOWLOON RAILWAY: 
CHINESE SECTION. 

By FRANK GROVE, M.Inst.C.E., and 
BASIL TANFIELD BERIDGE BOOTHBY, AssocM.Inst.C.E. 

The following is a short abstract of a Paper read at the Ordinary Meeting of the 

Institution on January 28th, iqij. 
This Paper is in two parts, the first, by Mr. Grove, dealing with the genera] c truc- 

E 2 20I 



THE INSTITUTION OF CIVIL ENGINEERS. [CONCRETE] 

tion and equipment, while the second, by Mr. Boothby, is an account of the largest 
two bridges of the East River Delta. 

The Canton-Kowloon Railway has been constructed in two sections : one, eighty- 
nine miles in length, in Chinese territory, from Canton to the Shum-chun River, the 
northern limit of the British leased territory in the Kowloon peninsula; the other, 
twenty-two miles long, through the latter territory to Kowloon. The former section 
has been built by the British and Chinese Corporation; the latter by the Colonial 
Government. 

The Chinese section of the line crosses the East River at Sheklung. The first 
thirty miles from Canton is alluvial plain not subject to heavy floods; the next twenty- 
six miles crosses the East River and its tributaries and is subject to heavy floods ; while 
the last thirty-three miles is for the most part hilly country with intervening plains. 

The East River valley, which is about forty miles in width, is deltaic, and in the 
ten miles between mile 31 and mile 41 there are seven bridges, aggregating thirty-one 
spans, with a total length of 3,248 ft. 

The cultivated ground throughout the East River valley length is 7 ft. to 11 ft. 6 in. 
below the highest known flood. For purposes of cultivation the whole area is protected 
by high bunds or banks. Formation was carried 2 ft. 6 in. above the highest flood 
record for thirty years, which gave a bank averaging for many miles 14 ft. high, and 
at approaches 24 ft. or more. These banks have been protected against wave- and 
flood-erosion by stone pitching. In times of excessive flood many miles of this portion 
of the line will be a causeway through open water 8 or 10 ft. deep. Its security will 
be aided materiallv by proper maintenance of the pitching ; while the fact that floods 
tise slowly and backing up takes place evenly on both sides of the bank gives additional 
security. 

Earthwork and all other works were carried out by petty contract. About 350 
contracts were entered into with Chinese contractors. Day-labour gangs were mostly 
confined to special bridgework, such as caisson-sinking, pumping, etc. 

The minor bridges and culverts and all the large bridges but three were built in 
cement concrete. Good cheap cement and good sand were procurable locally ; but the 
objection of the Chinese to quarrying their native hills gave rise to considerable 
difficultv in obtaining stone, and granite for the larger bridges had to be brought from 
Hong-Kong, although good local stone was plentiful. 

The steelwork for the bridges was designed by the consulting engineers to the 
British and Chinese Corporation (Sir John Wolfe Barry and Mr. A. J. Barry), and 
was built in England under their inspection. It was designed generally in accordance. 
with the standard Indian practice, but for a standard loading 10 per cent, above the 
Indian standard loading of 1903, having regard to the probable requirements of the 
future. 

There are fourteen stations and thirteen halts. With the exception of the Canton 
terminus, all the stations are of the simplest character possible having regard to exist- 
ing requirements. The platforms, except at Canton, are 6 in. above rail-level. 

The two bridges described in the second part of the paper are those over the East 
River and the Tung Kun River. Each has two shore spans of 60 ft., consisting of 
plate girders, while the waterway is bridged in the former with three and in the latter 
with four 224-ft. spans of Warren girders. The East River at Sheklung has a 
maximum tide of 3 ft., and its low winter level is 7 ft. above Admiralty datum at 
Hong-Kong. 

Borings showed red marl at 30 to 65 ft. below low water; the overlying material 
varied between sand and mud, coarse sand predominating. It was proposed to sink 
caissons 2 or 3 ft. into the marl, but it proved to be practically rock, and the depth 
proposed could not be reached. 

A contract for the concrete and masonry was let to Mr. Y. T. Chao, a Chinese 
contractor, and was successfully carried out by him, notwithstanding delays and 
obstruction and serious commotion among the populace caused by the importation of 
northern coolies. Well-sinking and girder-erection was carried out departmentallv, 
with petty contracts for riveting and other work where possible. 

Double octagonal caissons and curbs 38 ft. by 21 ft. <) in. were adopted for the 
piers of thf main spans, the Steelwork being built at Hong-Kong and sent up 1o 
Sheklung in sections. The bottom ring of each caisson was build on a cradle on 
Inunching-ways, and, when riveted and caulked, was launched. The second and third 

202 



f3j.ooN.vTBucnoNAi3 THE CANTON -ROW LOON RAILWAY. 

rings, making a total bright of 23 ft. GEasl River caissons) wen-, then added, and when 
concreted to a draught of i<> ft. the caisson was towed to the site, its position being 

adjusted by anchors. The caissons for the Tung Klin bridge were 14 ft. dee],, and of 

two rings only. They were built at the East River launching-ways and had to be towed 
and warped three miles to the Tung Kun bridge, which, owing to the resistance off< n d 
b) each double octagonal caisson in even a moderate current, proved to be a very 
troublesome task. One caisson broke loose and fouled the caisson for No. 3 pier of the 
East River bridge, which was in position ready for pitching and already concreted to a 
draught of [6 ft.; two days later both caissons were carried down-stream together, but 
were stopped l>\ the deeper grounding on a sandbank about a quarter of a mile below 
the bridge, whence both were recovered. 

Concrete was used for steining the walls, and was brought up in lifts of 4 to 7 ft., 

the same shutters being im d ever and over again. On the whole the use of 

proved very satisfactory, especially in giving weight for sinking, which, in the author's 
opinion, is of the utmost importance. The double octagonal caisson-walls were 
5 ft. h in. apart, anil this thickness was carried up in the well-walls until the pier- 
footings were reach d, providing a sinking force of 5 cwt. to 8 cwt. per sq. ft. of under- 
ground surface when the well was nearing foundation-level. 

In the foundations of two of the Tung Kun piers steeply sloping sandstone rock 
was encountered, and the caisson of one pier tilted 1 ft. q in., divers finding that while 
the west side was in the rock the east side was still in sand. The east well was then 
filled with sand, and by blasting around the cutting edge in the west well the pier was 
sunk another 1^ ft. As it was found that the east well was then on rock all round, 
the pier was founded thus, the masonry having to be partly dismantled and rebuilt owing 
tc the tilt of the pier. 

The 224-ft. Warren girders have eleven bays, which are 21 ft. between the centres 
cf triangulatiun both vertically and horizontally. They are for a single line, and are 
decked with |-in. steel plate, the rails being carried on longitudinal hardwood sleepers. 
The complete weight of each 224-ft. span is about 350 tons. 

After being erected one behind the other on shore, the spans were pushed forward, 
by means of hydraulic jacks, on to the ends of launching-jetties, and there lifted on a 
crib of sleepers by 100-ton ship jacks. Docks had been prepared inside the launching- 
jetties and when a span had been raised to the proper height on the jetties pontoons 
were brought under in a flooded condition. On these pontoons, when pumped out, the 
spans were floated into position. Each launch took one and a quarter to three hours. 

Mr. Grove was the Engineer-in-Chief, Mr. Boo>thby being the District Engineer of 
the Second Section. 



20} 



NEW WORKS IN CONCRETE. 



[CONCRETE] 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reliable information -will be presented of new ■works in course o) 
construction or completed, and the examples selected "Will be from all parts of the "world. 
It is not the intention to describe these "works in detail, but rather to indicate their existence 
and illustrate their primary features, at the most explaining the idea "which served as a basis 
for the design.— ED. 



NEW BUSINESS PREMISES IN REINFORCED CONCRETE AT 
MIDDLESBROUGH. 

The following are some particulars of the new premises recently opened for Messrs. 
New-house, Ltd., in Middlesbrough. The premises comprise large drapery stores, and 
reinforced concrete formed the chief constructional material, it being used for the 
entire internal construction. There are some unusual features in this particular 
building to which we would draw attention. 

Owing to the impossibility of obtaining sufficient depth for some of the main 
beams carrying exceptionally heavy loads, spiral armouring was introduced into the 




Section. 
New Premises for Messrs. Newhouse, Ltd., Middlesbrough. 



top part of the beams at the centre of the span so as to increase the resistance of the 
plain concrete and thus enable the designers to exceed the usual limit of stress in 
concrete of 600 lb. per sq. in. 

Our illustration an page 206 shows the reinforcement of a beam of this type in 
position. It will be noted that the stirrups are hooked into the concrete at their upper 
extremities. 

The irregular shape of the site also made the question of designing the beams 
particularly difficult, as the bending moments had to be calculated for points and 
distributed loads of varying amounts on beams continuous over spans of different 
lengths. 

To give some idea of the size of the premises, we would mention that the total 
area of the ground floor, exclusive of window space, is zN,.^) sq. ft., the showrooms 
and fitting-rooms have an area <>f 2,513 sq. ft., whilst the workrooms occupy 3,863 ft. 

204 



To r constbuctionaD 



REINFORCED CONCRETE BUSINESS PREMISES 





m 

Q 

Q 



2 



NEW WORKS IN CONCRETE. 

The use of reinforced concrete in buildings of this kind is of the greatest advantage 
and importance on account of its fire-resistance. 

The designs of the reinforced concrete system here adopted were those of the 
Considere Construction Co., Ltd., of Westminster, S.W., and the work was carried 
out bv their licensee contractor, Mr. E. Newhouse, of Middlesbrough. 




Reinforcement of Beam. 
New Premises for Messrs. Newhouse, Ltd , Middlesbrough. 

CONCRETE BLOCK COVE TO SHAND WALL. 

The wall illustrated on page 207 is made of " YVinget " blocks, and is 388 ft. long and 
19 ft. 6 in. high, 3,713 blocks being used in its construction. The blocks were built on 
the batter and kept slightly in advance of the depth of shuttering at the back when 
concrete in situ was filled in. The work was carried out by the Ilfracombe Urban 
District Council under the direction of Mr. Oswald M. Prouse, A.M.Inst.C.E., 
Surveyor and Harbour Engineer to the Council. 

Similar blocks were used by the Council on other works carried out by them, 
including Forty-steps Wall, the Manor Stables, the Stone Depot, etc. 



SOME AMERICAN EXAMPLES. 

CONCRETE MARKET HOUSE, FORT WAYNE, INDIANA. 
CONCRETE will enter most effectively into constructions of all kinds when its real value 
is understood, from the poinil of ornamentation as well as durability. 

The Market House, here described, is just south of the city hall. Its two pavilions 
are the chief decorative features of the structure, being connected by steel arches 
profusely strung with electric lights. There is a similar pavilion, no less ornate, at the 
further end of the structure. 

The entire length is 450 ft., and the width of the structure from curb to curb is 
26 ft. 5 in. The. general scheme of architecture is classical, the pavilions being ,,f fa e 
Ionic order. These pavilions, although built upon a core of brickwork, present an 
unbroken surface of concrete to the observer. It is concrete of a peculiarly pleasing 

205 



II 



OONSTPIJCTIONALl 
ENGINEERING- 



' — il 



REINFORCED CONCRETE IN AMERICA. 



SUifaoe, being made of while sand and Medusa white cement, with an agj 
bad's eye or roofing gravel. 

Winn the forms wore removed the surface was scrubbed with wire brushes, 
exposing the aggregate. The capitals of the columns were cast in glue moulds, and 

Other ornamental features, such as rosettes, keystones, etc., were cast in plaster moulds 




and set in place as the structure went up. The columns were cast in place in the 
same manner as the columns for the main part of the structure, hereafter desi i 
The drinking fountains were cast in place, complete with pipes, etc. These pavili 
contain the market master's office, as well as public toilet rooms, etc. In t! 
part of the structure there are fifty-four round columns, together with two squa 

207 



NEW WORKS IN CONCRETE. 



[C ONCRETE] 



columns at the and which backs up to the valley near the city hall. These round 
columns have a shaft of 8 ft. 9 in., resting on an octagonal base varying in height with 
the slope of the ground. The shaft of each column is 24 in. in diameter at the base, 
and 21 in. at the top, and each is surmounted with plain moulded capital and square cap. 




Concrete Market House, Fort Wavnk, Indiana, U.S.A. 



The method of construction of these columns is as follows : A rough core was first 

cast of a mixture of one to five. This core was made 6 in. less in diameter than the 

finished columns, allowing the finished cast to be 3 in. in thickness all round. When 

the core had hardened, the forms were removed and the mould was put in place around 

208 



[77CON5TCUCT10NA 
L&EMG1NEER1NG 



3 



REINFORCED CONCRETE IN AMERICA. 



this for the complete column. This mould was built of wood, in four sections, with 
very carefully finished surfaces, and into this was poured the finish concrete, of the 
same mixture as described for the surface of the pavilions. The proportions of this 
concrete were one of white cement, two of white sand and three of the roofing gravel. 
Medusa waterproofing compound was also used in all of the concrete to theextent of about 
i|or2 per cent, of the amount of cement. The forms were removed and the surface 
brushed after twenty-four hours. Long bolts were imbedded in the tops of the 
columns, extruding upward for the purpose of anchoring the roof. For the purj.oM- 
of accommodating these, a circular opening was cast in the caps of the columns, and 
this opening, after the caps were in place, was filled with concrete, thus serving the 
double purpose of holding the caps in place and also giving an additional anchorage to 
the bolts. 

The roof has a framework of wood, covered with red roofing tile. A con en te 
floor is laid over the entire structure. The tables are also of concrete, and 
are 112 in number, two tables being placed in each opening between columns. 
These tables are 5 ft. long, 2\ ft. wide, and will stand 2 ft. 10 in. above 
the floor. The legs are cast solid, but of slightly ornamental design. They 
are 4 in. thick, reinforced with a sheet of expanded metal, and were cast in a 
plaster mould, made in four parts on a wood frame. This mould simply consisted 
of the four sides clamped together and laid on concrete floor which was covered with 
oil paper. The concrete was then poured in, and the top trowelled off smooth. These 
legs and the tables themselves were made of a one to two mixture of ordinary grey 
cement and washed sand. The tables are if in. thick, reinforced with asheet of Page 
woven wire, and have a flange of about 3 in. extending around three sides, and they 

are also cast on a concrete floor in steel 
mould especially made for the purpose. The 
tables are bolted to the legs with four bolts, 
two being imbedded in each leg, and holes 
being provided for by the form for the 
tables themselves. These bolt Wholes are 
countersunk with a small trowel. 

The architects for this building were 
Messrs. Mahurin and Mahurin, and the 
contractors Messrs. Borkhenstein and Son, 
all of Fort Wayne, Indiana. 

SOME CONCRETE HOUSES IN A 
CHICAGO SUBURB. 

Our illustrations show some concrete 
bungalows recently erected at High Lake, 
one of Chicago's suburbs. It is reported 
that some forty houses in reinforced con- 
crete are also now nearing completion at 
Nanticoke, Pa., U.S.A., where the walls 
are entirely of cinder concrete built by the 
use of steel forms, as was the case with 
the houses illustrated on page 210. 




A 2-Ton Reinforced Concrete Door 
for Tunnel Work. 



SAFETY DEVICE FOR TUNNEL WORK. 
A Reinforced Concrete Door. — In connection with the new pressure tunnels now 
being driven beneath New York City for the Catskill water supply an interesting device 
is to be noted for storing the dvnamite used for blasting in the tunnel. A dynamite 
room has been hollo-wed out of the solid rock 250 ft. underground and connected to the 
tunnel by a narrow passage about 20 ft. long. At the end of this passage nearesl 
the storeroom a massive concrete frame has been keyed into the rock walls, bevelled 
at an angle of 20 . This frame has been fitted with a reinforced concrete door 
similarly bevelled, as will be seen from the illustration. This door is built up around 
five 15-in. I-beams with reinforcing rods passing through and between them, and it 
swings on a 3-in. steel pin. The weight of the door is 2 tons. The dcx>r is arranged 
to only open two^thirds the full way, and its objects are to reduce the force of t 
shock in the tunnel in the event of an explosion of stored dynamite and to protect the 

209 



NEW WORKS IN CONCRETE. 



[CONCRETE] 




A 




Concrbti Houses ni- \k Chicago. 



rt-foN^rcUcrioislALl 

UJLENQIKEEmNG — J 



REINFORCED CONCRETE IN AMERICA 



dynamite from excessive shocks from blasts in the tunnel, as in either case the door 
would be closed by the difference between the air pressures on the two sides. 

We arc indebted to the Engineering News, U.S.A., for our illustration and 

particulars. 

A REINFORCED CONCRETE HOTEL IN THE PHILIPPINES. 

Thr new Manila Hotel recently completed is reported as. being not only the largest but 
also the costliest structure in the Far East, and it is undoubtedly the largest in the 
Philippines. 

The building is constructed in concrete and steel throughout, with the exception 
of some of the floors and oeilings in the larger rooms, where highly polished Philippine 
hardwoods were employed. There are seven stories from basement-level. 

The hotel is well equipped; all the most modern steam and electric cooking 
apparatus being installed. There are steaming and refrigerating equipments on the 
roof garden floors and in the reception halls for heating and cooling food. 

Every convenience is to be found in the hotel in the way of large reception-rooms, 
billiard-rooms, etc. There are several roof gardens, verandahs, and balconies. 

The building rests on a solid foundation of hardwood piling driven to .a depth of 
52 ft. b in., and, with the grounds belonging to it, covers a verv extensive area. The 
grounds are laid out tastefully and attractively with lawns, shelled drives, sunken 
gardens, and fountains. 

The building was erected at a cost of nearly $50,000, and native labour was used 
to a great extent under the direction of American superintendence. 

We are indebted to Concrete-Ccmeui Age for the illustration and particulars of 
this building, as also of the houses illustrated on page 210. 




The N'evv Manila Hotel, Philippine Islands. 



NEW BOOKS. 



[CONCRETE] 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the leading books "which have appeared during the last fetu months. 



"Estimating for Reinforced Concrete Work." 
By T. E. Coleman. 

London: B. T. Batsford, 94 High Holborn. 143 pp.+x, 
price 4/- net. 

Contents. — Introduction — General Prin- 
ciples of Construction — Measurement 
of Reinforced Concrete Work — 
Materials for Concrete — Surface 
Finishing for Concrete — Prices for 
Concrete Work — Prime Cost of 
Materials for Concrete — Analysis of 
Prices for Concrete— Carpenters' 
Work — Materials for Centering — 
Prices for Centering, Sheeting, etc. — 
Analysis of Prices — Materials for 
Metal Reinforcement — Reinforce- 
ment Systems for Concrete — Prices 
for Smiths' Work — Analysis of Prices 
for Steel Reinforcement — Materials 
for Reinforced Concrete Piles — 
Systems of Reinforcement for Con- 
crete Piles — Prices for Reinforced 
Concrete Piles — Prices for Piles Com- 
plete — Ordinary Steel and Concrete 
Construction — Reinforced Concrete 
for Special Purposes. 
This is a very useful little book dealing 
with the measurement and pricing of re- 
inforced concrete work. A portion of the 
matter recently appeared in a series of 
articles in the Building News, and addi- 
tional notes and prices have been added 
and the whole carefully revised to date. 
The items and prices are based on the 
average cost of materials and labour in 
the London district, and consequently 
adjustments must be made, if necessarv, 
to suit varying local conditions. 

The materials for concrete, and also 
surface finishings, are described, and 
many useful tables are included in this 
section of the volume. Special chapters 
are devoted to the materials and prices 
for piles, and the various systems in use 
for general reinforced concrete are de- 
scribed and illustrated, although these are 
by no means complete; and this is also 
the case with the systems described in the 
chapter dealing with ordinary steel and 
concrete construction, as many important 
systems are omitted, and it would not 
have entailed very much time if these had 
been more complete. 

The volume i- well worth the price 
asked for it, and should prove very useful 

2 I 2 



to those connected with the question of 
estimating for reinforced concrete work. 

"Cassell's Reinforced Concrete." Edited by 
Bernard E. Jones. 

London : Cassell & Company, Ltd., La Belle Sauvage, 
E.C. 398 pp. + xx, price 15;'- net. 

Contents. — Introduction — What Rein- 
forced Concrete Is — Historical Notes 
— Concrete — Materials, Proportions 
and Mixing — Steel-Stress Simply 
Explained — The Theory of Rein- 
forced Concrete — The Erection of a 
Reinforced Concrete Building — 
Forms and Centerings — Systems De- 
scribed — Architectural and Surface 
Treatment of Reinforced Concrete — 
Durability of Reinforced Concrete — 
Waterproofing Concrete — Specifica- 
tions, Quantities, Measuring, Esti- 
mating and Pricing — Arches and 
Bridges — Examples. 
This new volume certainly deals with 
the subject of reinforced concrete in a 
manner unlike any other book that has 
been published in the country up to the 
present, as great attention has been paid 
to the practical side of the subject, and 
an endeavour made to produce a comnlete 
treatise that will be a guide to all those 
interested in the material, without assum- 
ing that the reader already possesses a 
certain amount of knowledge. The fact 
that various portions have been con- 
tributed by writers possessing a special 
knowledge of that portion of the subject 
with which they had to deal should 
naturally tend to produce a reliable 
volume, and we feel that the value of 
this book will be due in a great measure 
to this fact. The comparisons between 
plain concrete, steel and reinforced con- 
crete are interesting, and these are given 
bv means of diagrams and tables, which 
illustrate comparative sizes, weights and 
costs in a manner which give a good idea 
of the value of reinforced concrete as a 
structural material. Special mention 
must be made of the chapter on Forms 
and Centerings, which is illustrated with 
numerous excellent diagrams which cover 
almost every conceivable case that will 
occur in practice, from a small fence posl 
to a tall chimnev, and the whole of these 
are taken from actual examples, which 
enhances their value. The notes on the 
erection of a reinforced concrete building 



n 



OCNBTBUCTTON A l] 
EMOJNEERXNG — J 



NEW BOOKS. 



describe the method of carrying out a 

large factory, and they cover the arrange- 
ments for dealing with the various 
materials on the site, the plant and tools 
to be used, and the method of procedure 
to be followed in the actual execution. 

Owing to the extensive use of rein- 
forced concrete at the present time, and 
to the necessity of obtaining tenders for 
this class of work on a fair basis, con- 
siderable attention is now being paid to 
the question of preparing quantities, and 
we are glad to see that a chapter is in- 
cluded on this portion of the subject, 
although this does not deal with the 
matter as fully as would be possible. The 
theoretical portion of the subject is dealt 
with in a very simple, manner, every defi- 
nition and symbol being explained as fully 
as possible, in order that the reader may 
be quite conversant with the elementary 
principles. The reader should experience 
no difficulty in following the various for- 
mulae and calculations given, and more 
especially as the construction of the 
former are clearly shown step by step, 
and no knowledge of advanced mathe- 
matics is necessary. 

The whole volume is written and pre- 
sented in such a way that it should appeal 
to architects and students, who are often 
inclined to look upon the study of rein- 
forced concrete as a matter involving a 
tremendous amount of time and a good 
knowledge of higher mathematics, and 
they are apt to avoid the subject and leave 
this method of construction to specialists 
without being in a position to check the 
calculations or prepare a specification. It 
should form an excellent book of refer- 
ence for architects, and prove very useful 
to students preparing for examinations, 
and would, we consider, be a very good 
text-book for class purposes. 

"Transactions and Notes of the Concrete 
Institute." Vol. IV., Part III. 

Published at the Offices of the Institute. Denison House, 
296 Vauxhall Bridge Road, Westminster, S.W. 

This volume contains some notes as 
to the membership of the Institute, its 
library, and an account of various works 
and buildings visited. It also contains 
a paper, with illustrations, read by Regi- 
nald Ryves, Assoc. M. Inst. C.E., on. "Calcu- 
lations in the Design of a Thrust Buttress 
Masonry Dam," and a much belated one 
by Richard L. Humphrey, M.Inst.C.E., 
on " Fireproofing," read in 1911. These 
papers have already been amply reported 
in our journal. 



Spon's "Architects' and Builders' Price Booh 
and Diary." 

Published by E. & F. S|>on, I. id., 57 Haymarket, S.W. 
Price 5/- net. 

Spon's " Architects' and Builders' Price 

Hook and Diary for 1913 " is a most 
valuable reference book for all those con- 
nected in any way with the building 
trade. It maintains the high standard 
of former issues, and the prices, etc., 
have been thoroughly revised and brought 
up to date. The usual order of trades 
is adopted as in a well drawn-up bill of 
quantities, and there is also a fullv de- 
tailed index to these trades. 

LocKwood's "Builders' and Contractors 
Price Booh for 1913." 

Published by Crosby, Lockwood '<& Son, 7 Stationers' 
Hall, Lud^ate Hill. Price 4/-. 

This price book is published for the use 
of architects and surveyors and those con- 
nected with the building trade, and main- 
tains its very high standard. 

In this very useful handbook the first 
part deals with every class of building 
work, and the prices and wages tables 
have been carefully revised and brought 
thoroughly up to date. There is a sec- 
tion dealing exclusively with electric 
lighting, also a list of London district 
surveyors, and particulars of the boun- 
daries of their districts to accord with 
the changes made by the London County 
Council, as well as a list of surveyors 
of the various metropolitan borough 
councils and their addresses. 

In the appendices will be found tables 
of weights, areas, etc., solicitors' costs, 
stamp duties, tables for the valuation of 
leases and estates, legal notes and 
memoranda, and a great amount of other 
valuable information. A copy of the 
London Building Act, with its numerous 
amendments, is included. 

" Foundations and Machinery Fixing." By 
Francis H. Davles, A.M.I.E.E. 

London: Constable & Company, Ltd., 10 Orange Street, 
Leicester Square, W C. 152 pp., price 2 ■ net. 

Contents. — The Functions of Founda- 
tions, Nature of Soils and Piling 
Trial Bores — Design of Foundations 
— Design — The Proportions of 
Foundations for Engines, Turbines, 
and Dynamo-Electric Machinery 
Materials for Foundations — Holding- 
down Bolts and Anchor Plates Ex- 
cavation Construction of Founda- 
tions — Vibration : Its Cause- 



NEW BOOKS. 



[CONCRETE] 



Effects — Vibration : Methods of 
Isolating Machinery — The Fixing of 
Electric Motors. 
The question of the design and con- 
struction of proper foundations for ma- 
chinery is one that is very often over- 
looked, and this despite the fact of the 
great trouble that often arises through ex- 
cessive vibration, which tends to injure the 
machinery and create a nuisance to the 
occupiers of any adjacent buildings. The 
consideration of the most suitable founda- 
tion to adopt is undoubtedly the duty of 
every engineer who is connected with this 
type'of work ; but we agree with theauthor 
that it is a matter which also greatly con- 
cerns the architect, and co-operation be- 
tween the two parties is essential. The 
author deals very thoroughly with the 
points to be considered in the design of 
the foundations for various types of ma- 
chinery, and there are numerous useful 
tables and diagrams in the volume. The 
question of vibration is dealt with in a very 
interesting manner, and the examples 
given are sufficient to impress upon the 
reader the importance of making a study 
of this problem. Many remedies are given 
and various patent systems described, 
and there should be no difficulty in dealing 
with anv type of machinery provided the 
matter is fully considered in the first in- 
stance. YVe have no hesitation in recom- 
mending this little book to our readers, 
who will find it both interesting and 
useful. 

" Structural Design— Elemen's." By Horace 
R.Thayer. 

London : Con^uble & Company, Ltd. 221 + vii pp, 
price 6/- net. 

Contents. — Materials — Commercial 
Shapes — Wooden Structures — Fabri- 



cation of Structural Steel — The Engi- 
neering Department. 

The author has assumed that the reader 
possesses a knowledge of mechanics, 
stresses, and mathematics sufficiently ad- 
vanced to enable him to follow the for- 
mula?, etc., without any detailed explana- 
tion of the elementary principles. 

The greater portion of the book is de- 
voted to the practical rather than the theo- 
retical consideration of structural work, 
and it includes a full description of the 
fabrication of structural steel, together 
with notes on the organisation and ad- 
ministration in the shops and yards of the 
merchant. This portion is instructive, and 
contains a large amount of information 
seldom found in text books of this class, 
the examples described being all taken 
from American practice, as the author is 
engaged at the Carnegie Technical Schools 
at Pittsburg. The notes on materials in- 
clude timber, cast iron, wrought iron, 
steel, alloys of steel, and paints, and 
although these are not very full or in- 
structive in the chapter having this head- 
ing, there is a good description of the 
manufacture of the commercial shapes in 
the following chapter, which is clear and 
useful. There are a large number of pages 
allocated to the consideration of the pro- 
cedure in the engineering department 
which covers the preparation of specifica- 
tions, the designing of connections and 
members, the preparation of drawings, 
checking, examination of structures in 
use, and failures, and there are many use- 
ful hints and notes under th :se various 
sections. 

It should prove a useful volume, and 
indicates a thoroughness on the part of the 
author. which is commendable, and the 
various matters are presented in a clear 
and explicit manner. 



214 



1 



t'ONSTEOCTIQN 
ENQIMt^RING 



^ 



REINFORCED CONCRETE TENNIS COURTS. 



POPULAR USES. 



Under this heading it is proposed from time to time to present particulars of the more 
popular uses to ivhich concrete and reinforced concrete can be put, as, for instance, in the 
construction of houses, cottages and farm buildings-— ED, 



REINFORCED CONCRETE TENNIS COURTS. 

The question of reinforced concrete for tennis courts has of late aroused considerable 
interest, and, in view of the increasing demand for hard courts which shall be avail- 
able throughout the year, we present the following particulars as to how these courts 
were built in Northern Michigan, U.S.A. Our informant writes as follows :- 

In building the concrete tennis court here illustrated, a sand foundation was 
utilised, as the nature of the land was nothing but sand. The court was built the 
regulation size, allowing 4 ft. on all sides- for playing. It is 6 in. thick, reinforced 
with fence wire, the concrete being mixed about one to eight, and the facing a gfood 
mix, I in. thick. Care was taken to put expansion joints through the entire thickness 
of the concrete. These were made with a sand joint in the rough concrete, and the 
facing was merely cut through with a trowel when it was nearly set so as not to be 
roticeable on the surface. Any cracks resulting from changes in the weather will 
naturally follow these joints and in no way be conspicuous. The principal reason for 
reinforcing this concrete was that the climate in northern Michigan is rather severe 
through the winter, which would subject the court to unusual strain. In an ordinary 
climate this would scarcely be necessary. 

A pitch of 3 in. was made, the high point being in the centre at the net, and 
pitching back both ways. Drain tiles were set in along each side of the court and 
carried to a point of discharge. 

The boundary lines of the court were constructed by putting in a wooden strip 
1% in. wide, lined up perfectly true, and this is an important item, as an uneven line 
would be disastrous to the appearance of the court. After the top coat was finished 
these strips were removed and filled with white cement. 

It was the intention to secure a green surface for the court, and to this end the 
best green colour was procured, but this caused great disappointment, as, owing to 
the chemical action between the colouring and the cement, it faded to the natural 
cement colour. A cement paint was then used, which gives the court a very nice 




Reinforced Concrete Tennis Court, Michigan, U.S.A. 



POPULAR USES. 



[CONCRETE] 



appearance, but, our informant states, it will not endure for more than a season, when 
ii will have to be repainted. 

It was endeavoured to find a guaranteed green colour for cement, but so far 
without success. It is very easy to get a brown colour, which serves the purpose just 
as well, but painting is not recommended as it only lasts a short time. 

Care must be taken to get the court perfectly level, except in the direction of the 
pitch. 

The court above described was built by Mr. F. H. Beaumont, contractor and 
builder of Cadillac, Michigan, and we are indebted to him for our particulars and 
illustrations. 




Reinforced Concrete Tennis Court, Michigan, U.S.A. 



2l6 






, CON.STPIK.TION A L"| 
ENGINEERING — J 



MEMORANDA. 

1 




Memoranda and Netus Items are presented under this heading, "with occasional editorial 
comment. Authentic neivs tDill be "welcome. — ED. 



The Concrete Institute. — An interesting paper was read on February 13th at the 
Thirty-second General Meeting by Mr. S. Bylander, Chairman Junior Institution of 
Engineers, on " Steel Frame Buildings in London," of which a short report will be 
published in a subsequent issue. 

The Concrete Institute have formed a special Investigation Committee for the 
purpose of considering the action of the Local Government Board in respect to loans 
for reinforced concrete construction, and the committee will be pleased to have any 
information which can be furnished upon the matter. Among other things, the 
committee is desirous of obtaining information as to specific cases in which the Local 
Government Board (a) have refused to grant a thirty years' loan period, (b) have 
granted the full period. 

Scottish Junior Gas Association. — A paper on the " Construction of a Gasholder 
in a Reinforced Concrete Tank " was read in the course of the month bv Mr. G. P. 
Mitchell, of Dundee. The paper referred to the increasing of the gasholder storage 
?t the Alloa Gas Works by utilising a brick-built tank containing a single-lift holder 
o: a capacity of 75,000 cu. ft., increasing the depth of the tank by constructing a wall 
of reinforced concrete, and erecting in it a three-lift holder equal in capacity to 
280,000 cu. ft. 

Apart from the necessity of increasing the storage capacity of the works, the 
single-lift holder had been constructed so that the pressure thrown was only 22-ioths. 
For several years the gasholder had been of almost no practical value, as the day 
pressure required to meet a largely increased demand for gas for engines and cookers 
is 30-ioths. 

The old tank was brick built, having a puddle bottom. It was erected in the year 
1862, and had proved watertight, and, generally speaking, was known to be in a 
satisfactory condition. The work of emptying the tank was completed in twenty-five 
hours. 

On examining the tank it was found to be in splendid condition. As a precaution, 
however, it was decided to point the brickwork with cement ; and after picking the 
joints, the walls were thoroughly washed with a pressure of water from a hose, 
preparatory to cementing, in order to clean out the joints. 

The rest blocks had to be replaced by new ones, due to the difference in centres. 
Tbev were made of cast iron and laid on a concrete foundation. 

The required depth of the new tank being 20 ft. q in., it was necessary to raise 
the existing wall bv 5 ft. ; and consideration was given as to whether this should be 
brick built or reinforced concrete. It was ultimately decided to build a reiniforoed 
concrete circular wall to the required height. The reasons for adopting reinforced 
concrete instead of brick were as follows : (1) The relative lightness of the additional 
dead load superimposed on the old brick, wall. (2) The superior watertight m~- of 
reinforced concrete over brick — more especially in this case, where the superimp 
wall is not backed b<- clay, but is entirely above ground. (3) The reliability of rein- 
forced concrete against the bursting pressure of the contained water. 

The inside diameter of the tank wall is 81 ft. 11 in.; and the thickness of the 
reinforced concrete circular wall is 8 in. 

Having stripped 15 in. off the coping of the old wall, a 4^-in. channel was cut out 

f 2 217 



MEMORANDA. [COSCiaETB 

hi the centre of the brickwork- thus forming a groove and binding the old and new 
work together. 

The. standards of the gasholder are carried on ten reinforced concrete buttresses, 
equally spaced round the outer circumference of the tank ; and the foundations of these 
buttresses were carried right down a considerable depth to a hard subsoil. In front 
of each buttress 4-5 in. of the brick wall of the tank were cut out so as to tie the 
concrete to the old" brickwork. In each buttress a vertical bar was placed at each 
corner, and kept in position by f-in. diameter bars at 6-in. centres. The buttresses were 
brought up to the ground level before cementing to the wall. After the concrete had 
set, the space left was filled in with puddle, which was well watered and rammed in. 

After excavating for the new iS-in. diameter inlet and outlet pipes, the concrete 
foundation for the drip-box was laid. A hole was cut through the wall to allow for 
the length of pipe ; and a suitable concrete foundation was made inside the tank to 
leceivethe duck-foot bend. The drip-box, length of pipe, and duck-foot bend were 
then set in, connected together, and carefully tested. Concrete was packed round the 
drip-box and bend until the top of the pipe was covered, the wall being rebuilt and 
puddled inside and out. 

The ground being cleared and levelled, the work of erecting the wall was started. 
The horizontal reinforcing bars of the reinforced concrete wall are carried into the 
buttresses ; but the wall itself was sufficiently reinforced to resist the bursting pressure 
of the contained water without the aid of the buttresses. For this purpose the main 
tensional reinforcement is carried horizontally, and the sectional area of the bars is 
reduced from the bottom upwards in proportion to the pressures. All horizontal bars 
were overlapped 4 ft., and thoroughly anchored in the concrete at their ends by means 
of right-angle bends; and vertical bars were also placed, staggered at back and front 
t-f the wall, to distribute the stresses — the two sets of bars forming a complete 
grillage of steel in the concrete. 

At the top of the reinforced concrete wall a gangway or platform 1 ft. S in. in 
bieadth was formed right round the tank, projecting in cantilever form from the wall 
1 ft. S in. This was also constructed in reinforced concrete 4 in. in thickness. 

The total weight of steel reinforcement used in the reinforcement of the wall, 
gangway, buttresses, and their foundations was 6§ tons. All steel used was ordinary 
c Mnmercial rounds. 

The concrete used for the wall was made in the following proportions : Gravel, 
free from sand, and all to pass the f-in. ring, 27 cu. ft.; sand, 13^ cu. ft.; Portland 
cement, y\ cwt. This gave a particularly close-grained and dense concrete; and the 
concrete was also thoroughly consolidated when in position between the centering 
boards by means of vigorous ramming. No waterproofing compounds were used in 
the concrete, nor was any rendering of the wall after completion done. But after the 
removal of the boarding the surfaces of the wall were brushed over with two separate 
coats of Portland cement grout, thoroughly well rubbed in. The reinforced concrete 
wall, since being brought into use, has been found watertight. This portion of the work 
has proved eminently satisfactory in respect of efficiency and economy in capital cost. 

A Very Large Reinforced Concrete Column was tested in the Pittsburgh 
Laboratory of the U.S. Bureau of Standards on December 14th, 1912, before a 
delegation from the National Association of Cement Users, meeting that week in 
Pittsburgh. It is reported to be the largest reinforced concrete column ever loaded to 
de-aruction. It was a hooped column 16 ft. long, 30 in. in diameter, with a core 
diameter of 27 in., giving a total core area of 572-35 sq. in. The reinforcement 
ci r,>istrd of Mvcn longitudinal i-fs-in. round rods, a ^-in. wire helix, with 3-im pitch 
and thirty-one flat spirals of No. 5 wire of three turns spaced vertically 6 in. centre to 
centre. The column commenced to show signs of distress about 1.500 lb. per so. in., 
M.re area, and failed at a total load of 1,800,000 lb., or about 3,100 lb. per sq. in., 
core area.- -Engineering News. 

Uruguay. — In order to facilitate the handling and storage of goods discharged 
from vessels at Uruguay, four large depdt sheds have jusl b* en inaugurated. Each 
shed measures too m. by 45 m., has two floor-, and is solidly constructed of iron and 
reinforced concrete. A third floor ran easily be added if required. The work was 
carried out under contracl with the Goveromen't by the German General Building 
Co., Ltd. 

218 



f j, CONSTRUCTIONAL' 
K i LNT.1NLILR1NG — , 



MEMORANDA 



Square Inches of Sieel per Lineal foot 

o: 0.4 0.6 03 1.0 1.2 14 16 1.8 2.0 2. 2 24 't& 26 



Concrete Chimney of Interesting Design— \ concrete chimney recentl . 
at a steel plant near Hamburg has many interesting features besides its great height 
of 328 ft. Anion- these are its acid-resisting lining, made absolutely necessary b 
the purpose of the chimney is to carry away smelter-furnace gases; the special heat- 
resisting lining which extends from the top of the base to a height of 66 ft., and the 
massive nature of the chimney's base. 

The chimney, which is round in shape, tapers from an outside diameter of jo ft., 
at the base, to n ft., at the top, where the free opening is 9 ft. in diameter. Imme- 
diately below the chimney proper i- an underground vault, 13 ft. in height, which 
serves as an inlet for the gases. 'This is octagonal in shape, 36 ft. in diameter, at the 
base, and 31 ft. in diameter, al the top, and rests on a concrete block 7 ft. thick and 
42 ft. in diameter, which is in turn supported by 237 wooden piles, the space around 
and between which is filled in with concrete. The reinforcing of the chimin \ 
consists, in part, of forced-iron rings imbedded in the concrete at intervals of about 
6 ft. throughout the entire height. 

Designing Diagram for Cantilever 
Reinforced Concrete Retaining Walls. — 
Mr. W. D. Hudson, of the Missouri-Pacific 
Railway Co., St. Louis, Mo., states he has 
found the aocompanying diagram convenient 
in designing L-shaped reinforced concrete 
retaining walls. The purpose of the diagram 
is to ascertain quickly the proper thickness 
and reinforcement under different condi- 
tions of loading of the vertical slab in walls 
of the type shown in section on illustration. 
Its use may best be explained by means of 
examples traced out on the accompanying 
diagram. 

Example 1. — To design the vertical slab 
at depth 15 ft. for a wall with surcharge 
angle of 30 and angle of repose 30 — i.e., ' 
D = 15, = 30°, 0=30°. 

At depth 15 on the left-hand ordinate, 
proceed horizontally to the heavy dashed line 
A — A, and read on the nearest " thickness 
curve " 20 in. Proceed thence vertically 
upward and read at top of diagram 1*84 sq. in. 
per lictiu ft. for the amount of reinforcing. 

In case any other thickness is required 
by other conditions, the reinforcing area is 
read in the same manner — thus, if 26-in. 
thickness is required, reinforcing area equals 
i"4 sq. in. per lin. ft. 
Example 2. — To design a slab at depth 15 ft. for a wall with level surcharge and 
friction angle — i.e., D = 15, = 0, = 30°. 

Where depth 15 intersects curve marked "0 = 30", = 0," proceed vertically 
to curve marked " Reference Line," thence across to dashed line A — A, and read slab 
thickness 13-i in. Verticallv above read reinforcement of 1^24 sq. in. per lin. ft. 

The thicknesses of slab given are net thicknesses. Stresses used are : Tension in 
steel, 16,000 lb. per sq. in. ; compression in concrete, 650 lb. per sq. in. ; straight-line 
formula used in the analysis. As mav be seen, the slab may be designed for five 
different conditions of loading. 

It should be noted that the size of the base slab must be determined by some other 
means than given by this diagram. 

For Any Slab. — The diagram can be used for any slab of known bending moment, 
as follows : Locate the bending moment on the scale at the foot of the diagram, follow 
upward to " Reference Line," and thence follow horizontally to the appropriate -bib 
curve. Of course, where the horizontal meets the flashed line, the most economical 
thickness and reinforcement are found — i.e., the design which realises the full all 
stresses in concrete and steel respectively. — Engineering News. 

2 10 




S~ &~ £" $ ? & 8 J5 8 !£f 2" *< 

Momen+s in Poof-pounds 

Diagram for the Design of the Vertical 
Slab in Cantilever Retaining Walls. 



3o ( 




**- 



*«ar 



CONCEETfX c 



— bot, !§ 




UNHVEIRSAL JOUST 
STEEL SHEET PULE 




Used by 
all the 
leading 
Con- 
tractors 
through* 
out the 
world. 



Illustration showing our 15 in. X 43 lb. Piling being 
driven round Bridge Pier at Orleans, France. 

The Piling That Has Never Failed 



Telegrams : 

" Gramercy, " 
London. 

Telephones : 

1414 Avenue. 
1414 Central. 



All Particulars from 



BRITISH STEEL PILING C° 

Dock House, Billiter Street, LONDON, E.C. 



Please mention this Journal -when -writinQ. 



A ENGINEERING — , 



MEMORANDA. 



Lining a Deep Shaft with Concrete. The 1,017-ft. Kingdom double-compart- 
ment shaft of the Old Dominion Company at Globe, Ariz., has been lined with concrete 
delivered from the surface through a 4-in. pipe. Work was started near t] v and 
carried on in lifts from 150 to 220 ft. high. Temporary timbers were placed along the 
sides and ends and across the centre of the shaft at the bottom of each section and 
forms were built upon them. A permanent reinforced concrete bearer, 4 or 5 ft. high, 
was placed at the bottom of each lift. The forms were in 12-ft. sections and th 1 
was made to run from a mixer at the top of the shafl into a hopper and down the 
shaft through the 4-in. pipe to the point where it was needed. At the lower end this 
pipe discharged into an ordinary steel bucket suspended from the finished portion of 
the lining above. In the side of the bucket was a hole connecting with a short steel 
chute which delivered the concrete directly into the forms. The E}i£inccri>ig and 
Mining Journal states that the concrete was dropped successfully in this manner for 
a distance of over 1,000 ft. in building the last section of lining. The mixture was fed 
in regularly at the top and upper end of the pipe closed by placing a piece of canvas 
over the opening to stop the air current in the pipe and check the velocity of the 
concrete. The mixture was so dry that no water appeared upon the surface after being 
well worked. Had a wetter mixture been used the water would have separated from 
the sand and stone, taking the cement with it and leaving a lean concrete behind. The 
long walls of the lining were given a maximum thickness of 10 in. Old water pipes 
were cut into short lengths and placed in the concrete for weep holes through the wall. 
The concrete was a 1:3:6 mixture with the coarse aggregate varying from 5 to 1 in. 
in size. With twenty-five men working two shifts daily the time consumed in placing 
the lining was eight months, although the actual work of concreting was done in 
100 days, or about 40 per cent, of the time consumed. Each of the two-shaft compart- 
ments is 5 by 7 ft. 2 in. inside the finished lining. The concrete lining, which was put 
in after the former wooden timbering had been destroyed by fire, gives 60 per cent. 
more shaft area. — Engineering Record. 

TRADE NOTICES. 
The Leeds Oil & Grease Co. — We beg to draw attention to the concrete 
mould oil supplied by this firm for the purpose of preserving concrete moulds. The 
main points claimed for the grease are as follows : — 

Utility. — The improved quality of the work when the oil is used, and the fact that 
it does not deteriorate the work as many oils do. This latter point is important in 
\iew of the paper given at the Concrete Institute re the damaging effect of oils on 
concrete. 

Economical. — Low in price, easily applied, large covering capacity, always ready 
for immediate use. 

Wood Moulds and Shutters. — When used on these it saves its cost many times over 
from the fact that to a large extent it prevents the timber from warping — hence the 
t'mber can be used many times where if it warped it would be of no further use. The 
timbers leave clean, and neither the face of work nor the timber is damaged in removal. 
The Armoured Tubular Flooring Co., Ltd., state that they have used this grease 
for some years with satisfactory results. The method they adopt is to very slightly 
grease with the oil the face of the board upon which the wet concrete is moulded, and 
when it is sufficiently hard they have always found it leave the moulds in a perfect 
condition. 

The oil is at present also being used by Messrs. Perry & Co. in their work on 
the new Stationery Office. It has also been used on sewerage works, and it is also 
stated that such firms as the Engratic Patent Stone Co. and the Thames Patent Stone 
Co. use the oil. Full particulars are obtainable from the Leeds Oil and Grease Co., 
Chadwick Street, Leeds. 

Chubb & Sons' Lock and Safe Co. Ltd.— This company is making doors in a 
solid slab (2 in. thick) of reinforced concrete covered with steel plates of a special 
construction, which has just been patented. The doors are formed of two steel plates 
made to interlock in such a way that the interlocking pieces and the fastening rods 
inside between the two plates form the reinforcing members of thc> concrete filling, 
The concrete is put in from the open ends, which nee then closed by end plates proyidec 



MEMORANDA. [TONCREXE] 

with inturned and twisted pieces embedded in the concrete. Full particulars of these 
doors can be obtained on application to Messrs. Chubb & Sons. 

E. F. W. Grimshaw, The Reinforced Concrete Fence Posts, Ltd., have 
removed their office from West Mill, Buntingford, Herts, to 8, Broadway Court, 
Broadway, Westminster, London, S.W. 

CATALOGUES RECEIVED. 

Messrs. Ransome = verMehr Machinery Co. Ltd.— A new edition of this 
company's catalogue on concrete mixers has just reached us. 

The book is not only well arranged and fully illustrated, but contains much that is 
of interest and use. 

A full description is given of the various mixers supplied by the company and their 
applicabilitv to almost any kind of work demonstrated by the quotation of examples where 
the mixers and storage plants are in use. It will be seen that these appliances are 
equally useful for bridge work, hoppers, railway work, tunnel construction, road 
work, etc. 

There is also a section of the book devoted to steel piling and pile extractors. 

Copies of this catalogue can be obtained on application to the company at their 
address, Brunswick House, Westminster, London, S.W. 

Trussed Concrete Steel Co. Ltd. — We have also received a copy of this com- 
pany's new catalogue on their " Hy-Rib " system. 

The advantages of the Hy-Rib and its varied application, together with a descrip- 
tion of its method of manufacture, are dealt with at length and illustrated by means 
svf diagrams and illustrations. 

Specifications are given of how to apply Hy-Rib to walls, roofs, floors, ceilings 
and partitions, and the booklet concludes with an account of some tests to which this 
svstem of metal reinforcement was submitted. Copies of the catalogue are obtainable 
from the above-mentioned company at Caxton House, Westminster, London, S.W. 



BRITISH IMPROVED CONSTRUCTION CO. 

Telephone: 4067 Victoria. LTD. Telegrams: " Biconcrete, Vic. London." 

"BIC" 
47 VICTORIA STREET, WESTMINSTER, S.W. 



Manufacturers of all kinds of 

Concrete Constructional Materials 

(Plain or Reinforced) 

Including PIPES, PARTITION AND PAVING 
SLABS, SLEEPERS, STANDARDS & POWER 
TRANSMISSION POLES, HOLLOW BEAMS 
AND FLOORS, FENCING POSTS, etc, etc., 
by the well-known "JAGGER" PROCESS. 

Engineers' and Contractors' Own ^Designs carried out to order 

SPECIALITY. — Reinforced Concrete Pipes for High Pressures, abso- 
lutely Impermeable. Our Concrete weighs 156 lbs. per cubic foot. 



Please mention this Journal "u>hen •writing. 



CONCRETE 

AND 

CONSTRUCTIONAL ENGINEERING 



Volume VIII. No. 4. London, April, 1913. 

EDITORIAL NOTES. 



THE LOCAL GOVERNMENT BOARD AND REINFORCED CONCRETE. 

It is quite a current subject in these columns to have to complain of the apathy, 
not to say prejudice, with which reinforced concrete is still being' met at the 
Local Government Board's offices at Whitehall, and although we are quite pre- 
pared to say that there has been some slight improvement during the past few 
years, the fact still remains that an ordinary building of very poor construction 
is far more likely to be favourably considered than the best of buildings in rein- 
forced concrete when a question of loan period is. under review. 

Efforts, both official, semi-official and private, have been made to obtain 
some change in the Local Government Board's attitude, but, with some few 
exceptions as to individual cases, the general principle still seems to prevail of 
looking upon reinforced concrete with grave suspicion. 

We now assume, however, that some further effort is to be made to modify 
this unfortunate policy, which costs the ratepayer so dearly and makes the 
British Government a laughing stock among other civilised nations, who unwit- 
tingly attribute the inane conservatism of the Local Government Board to some 
grave matter of policy in the Government as a whole. 

The Concrete Institute, as will have been seen in our previous issue, is, it 
would appear, trying to collect information as to loans refused by the Local 
Government Board and the terms upon which loans have been granted, and this 
looks like some fresh systematic effort to obtain a remedy based upon reliable 
data. 

We would thub particularly recommend any public authority or professional 
man who has had experience of the Local Government Board's methods in this 
direction to immediately put themselves in communication with the Secretary of 
the Concrete Institute at Denison House, Vauxhall Bridge Road, Westminster, 
so that the Institute may have as full information as possible on this all- 
important subject. 

BUILDING EXHIBITIONS AND REINFORCED CONCRETE. 
In our March issue we gave some indication of the impending Exhibition at 
Leipzig, which is to be a Building Exhibition in the widest sense of that term, 
including architecture, science, construction, equipment and furnishing, and 

B 2 -21 



BUILDING EXHIBITIONS AND CONCRETE. 



[CONCRETE] 



having- regard to the excellence of the organisation and the many interesting 
building's in which the Exhibition is to be housed, the Leipzig undertaking 
certainly promises well. 

As to the rule to be played by reinforced concrete, it is a considerable one, 
both in the Exhibition structures and in the exhibits, and probably this Exhibi- 
tion will mark, if we may say so, the advent of the new reinforced concrete age. 

In London, too, we are to have our usual biennial Building- Trades Exhibi- 
tion at Olympia in April, which has a comprehensive display of the purely struc- 
tural side of building, combined with exhibits of technical equipment, which is 
certainly unsurpassed anywhere and does its organisers great credit. Here, 
however, we regret to say re inforced concrete only plays a minor or secondarv 
role, as the exhibits do not properly accord with the importance of the subject, 
and, in fact, we think that those concerned in reinforced concrete have been 
somewhat short-sighted in not arranging for more numerous and more extensive 
displays, in order to further their particular interests. 

Reinforced concrete exhibits there will, of course, be at Olympia, but 
nothing like what we might have expected at a period when reinforced concrete 
is not only so much in the forefront of discussion, but when it has to make its 
way at home with the aid of what might generally be termed advertisement. 

^Ye view Building Exhibitions, such as the one at Olympia and the wider 
one at Leipzig", as eminently useful to the trades concerned and the public at 
large. 

Just, however, as we anticipate that our Continental neighbours can take 
many a leaf from the book of the Building Trades Exhibition in London, so we 
also hope that we at home may be able to learn something from the Exhibition 
at Leipzig, and as this Leipzig- Exhibition, as indicated above, will have exhibits 
that specially appeal to our readers interested in concrete and reinforced con- 
crete, we would particularly remind those who are making plans for visiting 
the Continent during the current summer that a visit to Saxony may be both 
pleasurable and instructive. 



22 + 



E 



C'ONSTPUCTIONAI 
ENGINEERING — , 



REINFORCED CONCRETE BUILDING 



#rJ4->^ MESSRS. HARRODS' 




DEPOSITORY, BARNES. 




There are various points of particular interest in the building 
described in the following article, "which ivas prepared for us by 
Mr. Albert Lakeman, Honours Medallist Construction. — ED. 



This new building" has been erected at Barnes for Messrs. Harrods, Ltd., from 
the designs of Mr. William G. Hunt, F.R.I.B.A., and the use of reinforced 
concrete in a structure of this kind is important and illustrates how universal 
the material is becoming for all classes of buildings. The great aim of the 
architect has been to evolve a scheme which would give the greatest safety to 
the many valuable articles of furniture that will necessarily be stored in the 
building, while at the same time necessitating only the minimum amount of 
handling of the articles and the maximum amount of accommodation. The 
building (illustrated in this article), the erection of which is just completed, is 
intended to eventually form the centre block of a very extensive range of 
depository buildings, and is considered to be the most up to date and efficient 
building of the kind in this country. 

The principle of the construction may be described as that of a reinforced 
concrete frame building, all the constructional members being of this material, 
while the walls throughout are formed of 14-in. brick panels carried indepen- 
dently on the reinforced concrete frame, at each floor level. Similar interior 
division walls are used to subdivide the building into three portions, each of 
which is insulated from the others by means of fire lobbies having twin fire- 
resisting doors ; thus rendering' the spread of a fire from one division to another 
practically impossible. 

It is interesting and important to note that the adoption of this method, 
together with the use of reinforced concrete for the constructional members, 
enabled the important matter of insurance against fire to be effected under 
Class I. B., which calls for the highest standard of perfection which is recog- 
nised by the insurance offices for buildings of this class, and a considerable 
saving in premiums is in consequence made by the proprietors and their clients. 
In fact, the insurance offices regard not only each storey, but each of the three 
divisions of each storey, as a separate risk, just the same as il each division 
were a separate building. A fact of this kind should be sufficient to convince 
even those few persons who are still sceptical as to the value of reinforced 
concrete as a fire-resistant, and make the material more popular with those 
building owners who are apt to look upon it as being still in the experimental 
stage. 

The completed portion occupies an area approximately 125 ft. by no It., 
and it has five storeys in all, giving a total height from the ground floor level I 1 
the main roof of about 66 ft. The four floors above the ground floor, and also the 
roof, are cantilevered beyond the general face of the building for a distance of 

225 



REINFORCED CONCRETE BUILDING. [CONCRETE 

12 It., and the pantechnicon furniture vans arc driven directly on to a large 
electric lift, which is situated in the centre of the rear frontage, and are raised 

by this means to the floor required, the vans being- then drawn off the lift, 
along the cantilevered balconies, to the most convenient point, and there 
unloaded direct from the van to the actual spot where the goods are to be 
stored. This is obviously a great advantage, as the possibility of damage to the 
article is considerably lessened, and several vans can be unloaded at the same 
time without any confusion or inconvenience arising. These cantilevers are 
quite a feature of the building, and they are illustrated in the exterior view 
which is depicted in Fig. i, and they are described in detail in the subsequent 
notes. 




Fig. 1. Photographic View showing Cantilevired Balconies. 
Harrods' Depository, BARNf>. 

'1 he general arrangement of the constructional columns and beams is 
illustrated in the plan of the first floor in Fig. 2, there being fifty columns in 
all, and the details of the reinforcement, which were arranged by the Trussed 
Concrete Steel Co., will be found in Figs. 3, 4, 5 and 6. Some difficulty was 
experienced in the foundation work owing to the presence of water at a depth 
of 14 ft. below the surface, at which level a good Thames ballast was found. 
A large bloc k ol plain concrete was put in as a foundation for each column, the 
average size being H ft. 6 in. square, and on this the reinforced concrete base 
was commenced at a level of about 7 ft. below the ground floor. A typical 
detail is shown in Fig. 3, where it will be seen that this reinforced base consisted 
of a slab 5 ft. square, having a minimum thickness of <) in. at the extreme outer 

226 



s. 



coNSTBUcnasAU 

ENGINEERING -~-3 



REINFORCED CONCRETE BUILDING. 



(-•dyes, splayed upward towards the column to give a maximum thickness <>f 
18 in. at the intersection, to provide the requisite area for resisting- shear. This 
slab is reinforced on the lower surface with six Kahn trussed bars in each direc- 
tion, and four i-in. Rib bars are provided as anchors between the column and the 
base. The column is continued from the base to the ground floor level as a 
square column, having a 3-ft. side reinforced with six lines of vertical reinforce- 



/_ L^^ L'^'^T-'^ S'S. 



® 

^ — -^-----e>------- -*------- ©=~ = 

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§ ^ (ft © 

Oft-- -^- -- ^frlH^ -- <b = = if rZzdh =-■*-- -=+T ® = 




====---©== 

--^@ ------ -iUU---<^ 

-----44 



© 



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'a *?,» 2 6 m M**o ve* Ab of e v dews as starve' ( cfcepf este* ■ ,** bea*^S> 



©-- 



jf 



fe 



,^^--,-_^@:--- -_-^=-: .-_-.©: r, ^-^_-_-_-^= -_-_^=-_=^ 



== @— =— 4 



f 



^Ec© 1 "- 



-=@— --— ! 







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©=■-"= 






Fig. 2. General Plan of Columns and Beams. 
Harrods' Depository, Barnes. 



ment with spiral binding, and at this level it becomes circular for a height of 
12 in. before being reduced to an octagonal section as shown. The circular portion 
is protected with an iron kerb and sheathing to prevent damage by the vans. The 
whole of the upper columns are octagonal in section, as shown in Fig. 4, which 
illustrates a typical detail, and it will be seen that six vertical lines of reini 
ment are provided with spiral binding, giving a circular core. The binding is 
arranged to finish at the centre of the floor slab, and the vm\ is bent 9 in. into 
the column and hooked. The size of the column illustrated is about 1 ft. Q in. 



REINFORCED CONCRETE BUILDING. 



ICQNCREXFj 




Fig. 3. Detail of Column and Base. 
Harrods' Depository, Barnes. 



for the lower portion and i ft. 6 in. 
for the upper part, these dimensions 
being- taken between two opposite 
faces and at right angles to same. 

The interior columns are 
spaced in six rows across the width 
of the building, giving a distance 
apart equal to about 22 ft. centre to 
centre, and in each of these rows 
they are spaced at about 14 ft. 6 in. 
centres. The floors are constructed 
with main and secondary beams, 
the former having a span of 14 ft. 
6 in. and carrying the ends of two 
secondary beams on either side, the 
latter being arranged at intervals of 
4 ft. ioi in. These secondary 
beams are somewhat close together, 
but they required a depth of 18 in., 
as they span a distance of 22 ft. 



The width is 
8 in., and the 
r e i n f o rcement 
consists of one 
Kahn bar and 
three Rib bars, 
as illustrated in 
Fig. 5, where 
the main beams 
are also shown, 
and it will be (__ 
seen that these 
latter have a 
depth of 20 in. 
and a width of 
13^ in., while 
they are rein- 
forced for ten- 
sion with one 
i|-in. Kahn bar, 
two iB-' n - R'b 
bars, two f-in. 
Rib bars, and 
one 1 -in. Rib bar 



228 




Fig. 4. Detail of Column. 
Harrods' DEPOSITORY, Barnes 



CONSTKUCTIONA L\ 
F.NT.IM Egg I NO J 



fir CONS 
l<v F.lSGi 



REINFORCED CONCRETE BUILDING. 



■ft 



S 



It 



J 





u*h>A " 




Q - 



229 



REINFORCED CONCRETE BUILDING. 



[CONCRETE! 



\ 




Fig. 7. Section of Building. 




230 



Fig. 8. Interior View showing Columns and beams. 
Harrods' Depository, Barnes. 



r a, constbuctionaD 

l< I ENCfNt-E-RING —'J 



REINFORCED CONCRETE BUILDING. 



Continuity bars, ^ ft. long, are placed at 12-in. centres in the upper 
surface of the slab, these being |4n. Rib bars, and similar bars, 2 ft. long, 



* 7 




•O T. 

<u a. 

■S < 



are provided over the secondary beams, while ample provision ag 
is made as shown on the drawing in Fig. 5. It will be seen that all the beai 

231 



REINFORCED CONCRETE BUILDING. [CDNCRETEJ 



which are framed into the columns have brackets 2 ft. long- and 12 in. deep, 
and the general appearance of the finished work is well illustrated in Fig. 8, 
which is a photographic view of the interior. 

The floor slabs have a thickness of 4 in.., and these are reinforced with |-in. 
rib bars. The window lintels are continuous, and these form the beams for 
carrying the floor and wall above each opening - . 

The cantilevered balconies are shown in Fig. 7, which is a section through 
the building, and in Fig. 6, which is a detail drawing of this part of the work. 
These balconies are supported by six cantilevers at each floor level, which are 
provided by the continuation of the main floor beams at this point. The latter 
have, however, an increased section for the span immediately behind the canti- 
lever, as this forms the tailing down portion from the front column, which acts 
as the fulcrum. The balconies have a projection of 12 in. from the centre line 
of the column, and the slab which actually forms the floor of the balcony is 
carried by three beams, the two outer ones spanning between the cantilevers, 
and the inner one being supported directly by the columns. The beam at the 
extreme outer edge has a depth of iS in. and a width of 6 in., 
and is reinforced by Kahn and Rib bars, while the intermediate beam, 
which is formed midway between the columns and the outer beam, 
is 16 in. deep and 12 in. wide, with reinforcement as shown. The canti- 
levers have a minimum depth of 14 in. at the outer end, and this is increased 
to 1 ft. 10 in. at the centre of the projection and 3 ft. 2 in. at the junction 
with the column. Reinforcement is provided in the upper and lower 
surfaces, and stirrups are placed at 417-in. centres. The tailing down 
beam is also reinforced in the upper and lower surfaces, and similar stirrups are 
provided in the portion adjacent to the column. The floor of the balcony has 
a slight fall from either side toward the centre, and raised concrete curbs are 
formed to confine the wheels of the vans. The arrangement is admirably 
carried out, and the adoption of reinforced concrete for the cantilevers and 
balconies undoubtedly permitted the most suitable and economical form of con- 
struction to be executed. 

The building is effectively designed with terra-cotta dressings and facing 
to the front elevation, while the introduction of a cupola at the corners of the 
main front lends additional interest and gives a good sky-line. The weight- 
carrying members in these features are all constructed of reinforced concrete, 
thus giving a complete concrete frame to the whole building. 

The general contractors for the work were Messrs. Holland and Hannen, of 
Bloomsbury. 



232 



IS 



CONSTBUCI iONA 
LNGTNEERINO 



3 



PROBLEMS IN THEORY OF CONSTRUCTION. 




~~ 1 

PROBLEMS IN THE THEORY 
OF CONSTRUCTION, 

THE OBLIQUE LOADING OF BEAMS AND 
COLUMNS. 

By EWART S. ANDREWS, B.Sc.Eng. (Lond.). 



1 



The following article should be of interest to engineers tuho, in the course of their practice, 
must often have to deal •with the question of the oblique loading of beams and columns. — ED. 



CALCULATIONS arise occasionally in the practical design of beams and columns 
in which oblique loading has to be allowed for. By oblique loading- we mean 
"loading - whose plane does not contain a principal axis of the section," and 
where this occurs we cannot obtain the stresses by the ordinary bending 
formula?. In the case of columns, in which the point most commonly arises, 
" oblique loading " is a special case of " eccentric loading " and arises where 
the resultant load is eccentric and does not act down one of the lines of symmetry 
of the column. 

The principal difficulty is on account of the fact that the neutral axis for 
oblique loading will not be at right angles to the plane of loading. We will 
deduce the formula that can be employed for this case and will then explain its 
use with reference to the case of an obliquely loaded column. 

DERIVATION OF FORMULAE. 

Let Fig. i represent any section of a column or beam of which XX and 
YY are the principal axes. The principal axes of a 
section are those passing through the centroid at 
right angles to each other about which the moments 
of inertia are greatest and least respectively. 
If the section has an axis of symmetry, this axis 
will be a principal axis and the other principal 
axis will be at right angles to it. We will show 
Liter how to find the principal axes of sections 
which have no axis of symmetry. 

Let ZZ be the " plane of loading," or rather 
the intersection of this plane with, the section. In 
the case of ordinary beams, for instance, the forces 
would all be in the direction ZZ, and in tin case 
of columns the resuitant load will act at some point on ZZ. 

NN is the neutral axis of the section, which will in this case nol be al 
right angles to ZZ, but at some angle to A'.Y. 

Now consider an element of area a at a point /' at distances a, y , n from 
XX, YY and NN respectively. (In the position shown these quantities will, 
according to the usual convention, be positive.) 

2;; 




EWART S. ANDREWS. 



(CONCRETE) 




Then we shall have, since the stresses are always proportional to the 
distance from the neutral axis, /= stress at P = mn where m is a constant. 

Now if M is the bending moment, its components about XX and IT must 
be equal to the sum of the moments of the stresses on the section about these 

axes. 

. . . A7 sin A. = component of M about XX = ^f .§a ,y 

= 2 mn y°a (l) 

but n =y ccs u — -v sin a (2) 

[This can be seen from Fig. 2, which shows this 
part of the diagram redrawn to avoid confusion. 
PS=-n, PQ = y, OQ = x. PO and PR make an angle 
a with each other. OR is drawn parallel to 175 and 
07' at riedit angles to ON. 

Fig. 2. » & S 

Then y cos a-. v sin a = PR-QT = PR — SR =PS.] 
.'. M sin A- = 2 m {y 1 cos a — xy sin a) ha 

= m cos o^y 2 8a — m sin a^xy^a (3) 

now %xy$a is what is called the product moment of the section and this is always 

zero for the principal axes ; also ^.y z °a=Ixx 

. ' . M sin A =/;/ cos « /.v.v (4) 

Similarly M cos A =component of M about YY 

='2f.8 a .x 
= 2'»"-v . ?a 

= 2»z (y cos a — x sin a) x&a 
= m cos«2-vyS(7 — hi sin £>2-v 2 &« 
= 0—m sin alyy (5) 

Dividing (4) by (5) we get 

tan A 



— cot « . I xx 



cot a 



Ivy 

— Iyy tan A. 
~Ixx~ 



(6) 



This equation enables us to obtain the neutral axis. To get the stress at P 
in its most convenient form we can proceed as follows : — 
From (4) and (5) we get 

MsinA -M cos A 

m = - =— : 

I xx cos a / n -sin a 

Now f=mn =m {y cos a — x sin <*) 

= my cos « — mx sin a 

_ M sin Ay cos a / M cos Kv sin 

I xx cos a ^ /vi sin a 

M sin A. y Mcos A . .y /-\ 

I xx iyy 

Since this formula docs not involve a, the actual position ol the neutral 

axis is not required for the calculation of the stress at any point, but it is 

usually better to find the neutral axis, because the values of x and y required to 



23+ 



' j„ CONyTBUCTIONA CI 



PROBLEMS IN THEORY OF CONSTRUCTION. 



find the maximum stress will be those for the point at maximum distance from 

the neutral axis, and this cannot always be found until the neutral axis is 

drawn in. An example of an obliquely loaded 

beam arises in the ease of the cross beams ol a 

bridge inclined to the horizontal, the cross 

beams being fixed " square " to the main 

girders. 

In applying this treatment to obliquely 
loaded columns, it should be remembered that 
the value of I above is that due to bending- only, 
and this must be added to the direct stress per 
square inch equal to the load divided by the 
area. 

NUMERICAL EXAMPLE OF AN OBLIQUELY 
LOADED COLUMN. 

Take, for instance, a column of the section 
shown in Fig. 3. This is a corner column, 15 ft. FiG - 3 - 

long, and has loads transmitted to it at .4 and 

B of 30 and 40 tons respectively, the resultant of which is a load of 70 tons 
acting at D. We shall see later that this gives a very simple result. 

The following properties of this section are given in Dorman, Long and 
Co. 's Pocket Cotiipanion : — 

A=28'59 sq. in. 
k X x= 4'45 in. 
k YY = 3'39 in. 

AD 4 




D will divide A B in the ratio 



DB 3 



Measurement gives X= 1 10'4° 
. ' . tan X= -2'69 

28 '59X3'39 2 (-2'69) r g 



cot a [from equation 6] = 



28"59X4"4i 

3 '39'" 

,X269 



ince 1 = Ak 2 \ 



4'45 2 ' 
= 1*56 approx. 
.". a = 32'6° nearly 
The neutral axis comes, therefore, as shown IVJV in the figure; the line at 
right angles, which would be the neutral axis if the ordinary treatment applied 
to oblique loading, being shown in dotted lines. 

EO 4 5'55 
I. We could calculate tan A. by noting that tan A = — - = x .,.„ , = 2'69] 

tLU 5 ill 



M sin A w iH be equal to 70 x OD sin A = 70 X £0 = 70 X 



4 ■ 5\5 



220 in. -tons 



[This is the same as 40 X OB] 
McosA = 70X ODcosA=— 70XZ>E=70XfX2'72 = — 8T6 in. 

[This is the same as 30 X OA] 



tons 



235 



EWART S. ANDREWS. [CONCRETE ] 

The maximum stress will occur at the top left-hand corner, for which 

y = 5'5 in., x= — 6 in. 

. __ , ,. , 220X5-5 81*6X6 

. . Maximum bending stress = /=— — — — 7777-9+X^T- — ttt^? 

J 28 59X4 45 2 28 59 X 3 39 2 

= 214+1*49 

= 3'63 tons per sq. in. 

Direct stress = — — = 2'45 tons per sq. in. 

. ' . Combined stress = 6'08 tons per sq. in. 
Taking the safe stress by Rankine's formula 

6 






i 4-Aonn( 



l+600o( 1 ) 



6 

we get f P - i 5 x 12X15X12 = 408 tcns 

1+ T—— rr^ — per sq. in. approx. 

6000X3 39" 

On the above figures, therefore, the section is not quite strong enough. 

SIMPLIFIED TREATMENT. 

At the beginning of this example we remarked that it gave a simple result, 
the reason being that in this example the loads are applied on the principal 
axes. This will be seen by noting the facts that the Jl/sinA and .A/cosX come 
equal to the B.Ms for the two loads considered separately and that the formula 
for / then comes equal to the sum of the bending stresses for the two loads 
considered separately by the ordinary formula? with A* A' and YY as neutral 
axes. We get, therefore, the following simple rule for a column obliquely loaded 
when the loads are applied on the principal axes : — Calculate tin hauling 
stresses for each load separately and acid both these to the direct stress ; then 
the result should not be more than the safe central stress for the given column 
according to the standard column formula. 

EQUIVALENT CENTRAL LOAD. 

The most convenient way of dealing with the eccentric loading when a 
table of safe central loads for various column formula? is available is to find the 
equivalent central load. 

This may be done in the present case as follows :-— Let W Y and W x be the 
loads applied on the axes YY and A'A respectively, then equivalent central load 



= W l =Wy(l+^) + Wx(l - L /" V ,) 

x kx'x' A'vv 



Where e y , e x are the eccentricities of Wy and Wx and y, x are the distances of the 
furthermost points of the section from XX and YY respectively. 

1 1.1, ■ h/ — aaIi_l.5'5x5'5*\ an fi j_272X6\ 

In this case iv 1 — 401 1 + — ■ — ) -r30l 1 + - — 5- J 

\ 4-45- J \ 3-39-- / 

=40X2'52 +30X2'42 

= 174 tons nearly. 
Assuming that the present case is equivalent to both ends rounded [as we 
236 



I 



CONSTHUCTiaNA 1. 



PROBLEMS IN THEORY OF CONSTRUCTION. 



have done in Rankine's formula), the equivalent length according to Messrs. 

15 4 



Dorman, Long and Co.'s treatment is 



20 ft. Their tabulated ntral 



load for this section, 20 ft. long, is 145 ions, so thai on their figures also the 
section taken is too small for the loads taken. 

DETERMINATION OF PRINCIPAL AXES. 

We slated earlier in the article that we would 
indicate how to calculate the position of the principal 
axes lor a set lion with no axis ol symmetry. 

Let Fig. 4 represent any such section. 

Take any two convenient axes, UU and II', 
at right angles to each other, and also a third axis, 
WW, at 45 cleg, to either. 

Calculate (graphically or otherwise) the 
Moments of Inertia I uv I vv Iww : >bout these axes. 
Then the inclination /? of the principal axes to UU 
and VV is given by 

Tan 2,6 > -^ /c "r- + /vv-2/Yvv v 
I uu ivv 
The angle f3 is given in the tables of standard sections for Z and unequal /. 
sections, which are the only non-symmetrical sections which occur. 




23; 



REINFORCED CONCRETE IN SOUTH AFRICA. [CONCRETE] 




SOME RECENT EXAMPLES 

OF REINFORCED CONCRETE 

CONSTRUCTION IN SOUTH 

AFRICA. 



In a former issue we presented a description of the use of reinforced concrete in South 
Africa, and in continuation thereof ■we now give the following particulars of some work 
carried out b\> Mr. Edmund D. Pickford, of Johannesburg, ivho has prepared these notes 
and furnished us ■with the illustrations. — ED. 



The chief difficulties which militate against the more general use of reinforced 
concrete in South Africa, more particularly in Johannesburg- and inland towns, 
states Mr. Pickford, are the heavy cost of cement, labour and timber. 

The price of cement, for instance, varies from 31s. 6d. per cask in Johannes- 
burg to as much as 55s. in some of the chief towns in Rhodesia. 

This heavy cost is largely due to railway charges. 

The price of labour, too, bears more heavily than that of cement on the 
cost of reinforced concrete construction. 

The standard rate of wages for carpenters in Johannesburg is 20s. per day, 
while it varies from 25s. to 30s. in parts of Rhodesia. 

The mixing and laying of concrete is, of course, done by coloured labour, 
either Cape Bovs or Kaffirs, who are paid in Johannesburg about 3s. a day ; and 
although this is less than the wages of the English labourer, as one has, as a 
rule, to break in a fresh gang of concrete mixers for each job, and to pay for 
white superintendence, the cost of mixing and laying may be reckoned as at 
least equal to that in England. 

Even, as along the East Coast, where one pays as little as is. a day for 
native labour, the result is much the same, as the labour is less efficient and 
the necessary superintendence costs more. 

Labour-saving machinery is not economical, except in very few instances, 
as it involves white attendance, and the cost of transport and repairs at places 
away from towns is very heavy. 

Timber works out roughly at about twice the cost of that in England, and 
as most jobs are not conveniently placed alongside the timber yards, sometimes 
being two or three days' trek by ox wagon from the railway, it is necessary to 
calculate one's requirements in this direction very exactly, otherwise expensive 
delays are entailed. 

Further, in a new country, especially in the mining centres, it is nut the 
material which lasts longest or is most efficient that appeals to the employer's 
mind, but that which costs least ; therefore reinforced concrete has to compete 
against steel construction, which has been brought by competition to greal 



238 



r lr CONSTIMKTIONAl.) 



REINFORCED CONCRETE SWIMMING BATH. 



economy and efficiency, and againsl brickwork, the prices for which are fairly 
low throughout the country. 

However, despite these drawbacks, a lair amounl of work lias alread 
done in the country, and then- is no doubt that, with some competition in the 




.-is 




Swimming Bath, Durban, in course of construction. 

manufacture, and a consequent reduction in price, of cement, the amount of work 
would be vastly increased. 



2 39 



REINFORCED CONCRETE IN SOUTH AFRICA 



En^te] 



Swimming Bath, Durban. 

This bath is situated on the ocean beach just above high-water mark, and is 
300 ft. long- and 75 ft. wide, and is therefore one of the largest in the world. 

It was designed by 
.Mr. John Fletcher, 
M. Inst. C. E., the 
Borough Engineer. 

I he bottom is 9 in. 
thick with ribs at 10 ft. 
intervals reinforced as 
beams, and the sides are 
9 in. thick at the bottom, 
and taper to 6 in. at the 
top and are strengthened 
with counterforts above 
the ribs. The reinforce- 
ment consists of indented 
bars and a steel netting-. 

The work to the 
bottom was carried out 
continuously day and 
night, and, despite flood- 
ing by an unusually high 
tide, the whole of the 
excavation and rein- 
forced concrete w ork 
was completed in about 
nine weeks. 

Tube Mills Supports, 
Village Deep Gold Mine. 

This is one of the 
largest and most com- 
plete installations of tube 
mills on the Rand, con- 
sisting of six mills, each 
about 35 ft. long and 
5 ft. diameter. As the 
tube mills each weigh 
about 30 tons and make 
35 revolutions per 
minute it will be under- 
stood that a considerable 
mass of concrete would 
be required to withstand 
the vibration. As a 
matter of fact, this i^ 
scarcely noticeable even 
with all mills running. 
240 




r f, CCWSTBIICTIONALT 
[ft. ETSGTNE.EJMNG — J 



PREMIER MILLING CO. PREMISES. 



The reinforced concrete main beams have a span of 25 ft. and carry a 
platform calculated for a super 1 lad of 500 lb. per sc|. ft. The reinfo 
consists of mild steel rods, arranged on the Smith Pickford patenl system. 

The same type of construction was adopted at the Jumpers Deep 

Mine, hut in 
this case the 
height of the 
platform above 
ground w a s 
13 ft. instead 
of 10 ft., and 
there were only 
three mills. 

Premier Milling 
Co. Premises, 

Germiston, 
Johannesburg. 

This build- 
ing is con- 
structed e n - 
tirely of rein- 
forced concrete, 
the walls being 
6 in. thick with 
18 in. piers 
a n d wall 
beams, which 
carry the 
weight of the 
floors and 
machinery, on 
the same prin- 
ciple as a steel- 
framed build- 
ing. 

The centre 
portion of the 
building con- 
tains twelve 
b il(is lor the 
storage of 
mealies, each 
ft. square and 

45 ft- hi gT h - 
The reinforcement throughout consists of plain mild steel rods on the same 
system as the last. 




M 1 



REINFORCED CONCRETE IN SOUTH AFRICA, 



[iTONCBETEJ 



Travelling Excavator Supports, Crown Mines. 

These supports, which are about 30 ft. in height, carry a travelling 

excavator 

which weighs 
over 40 tons 
and has arms 
25 ft. in length 
fitted w i t h 
discs which 
rotate within 
the tanks 
ploughing up 
the sand. 
These arms 
each weigh 
about 2 tons 
and are driven 
at from 30 to 
45 revolutions 
per minute, 
and as in 
their rotation 




•Jf r 

Travelling Excavator Supports. Crown Mines. 




Premises for the Premier Milling Co., Germiston, Johannesburg. 

they encounter both sand and slime the strain on the supports is of a most 
trying descripl inn. 

The length of the supports is 250 ft. and the distance between rails is 47 ft. 



24 2 



TRAVELLING EXCAVATOR SUPPORTS 




There are I v o 
with a connecting turn- 
table, also consl rui ed in 
reinforced concrete. 

T h e reinforcement 

Consists Of round sleel 

bars from .', in. to i \ in. 
in dia. , and the uprights 

and beams were eased up 
and east in situ. 

The same design 
was adopted at the City 
Deep Mine, where the 
miners carried out the 
work themselves, but in 
this case the uprights 
were cast on the ground 
and raised into position. 

Ore Bins, Randfontein 
Central Gold Mine Co. 

These ore bins are 
placed near the 600 
stamp battery, and the 
ore is conveyed to them 
by a double railway track 
on which run 40-ton 
bogey trucks, having a 
side discharge. The 
capacity of the bins is 
about 1,500 tons, and the 
bridgework over them is 
open, consisting of rein- 
forced concrete main 
beams and stiffeners, 
which are calculated for 
locomotives of 17 tons on 
the driving wheels. 

The walls vary from 
9 in. to 6 in. in thickness, 
and are stiffened with 
counterforts and horizon- 
tal beams. 

T h e reinforcement 
consists of mild steel 
bars. 

Somewhat similar 



2 + 3 



REINFORCED CONCRETE IN SOUTH AFRICA 



[CQNCEEXE 




Native Compounds along the Reef. 



bins have also 
been con- 
structed for 
the Nourse 
Mines. 

Native 
Compounds. 

The writer 
has con- 
structed a 
cons iderable 
n u mber of 
these build- 
i n g s , suffi- 
cient, in fact, 
to accommo- 
date over 
10,000 boys, 
for various 
mines along 
the Reef. 
The principle adopted by him is that of casting- the walls in slabs about 

8 ft. in width by the height of the building, usually 10 ft., and raising them by 

means of a derrick. 

The thickness of the slabs is 3 in. , and they are reinforced with plain steel bars 

which project 

beyond their 

ends and are 

embedded in 

reinfor ced 

concrete but- 
tresses. 

This sys- 
tem admits of 

fairly rapid 

c o nstruction, 

the rooms, 

28ft. by 

25 ft., being 

completed at 

the rate of 

one in three 

days, includ- 

i n g founda- 
tions, roofs, 

a n d lowered 

ventilators. Reinforced Concrete Dam near J ihannbsburo. 




21 + 



I 



CONS! PIKTIONAL 
ENdWt.E-RlNC, — , 



REINFORCED CONCRETE DAM. 



ReinforcedkConcrete Dam. 

The accompanying photographs show the upstream and down iews 

of a reinforced concrete dam, designed and constructed on the farm, Rietvlei, 
near Johannesburg* 

It is probably the first dam of this type completed in South Africa, and 
takes the place of no fewer than four earth dams, which have heen carried away 

by the sudden Hoods, to which the supply stream, like most others in S 
Africa, is liable. 

The upstream face has an inclination of 45 , and is supported on reinforced 
concrete ribs spaced 10 ft. apart. The foundations are partly on rock anil partly 
on clay, ami are formed by a grid of reinforced concrete beams. 

During its construction it was exposed to severe frosts, and afterwards 
remained dry for five months, with a differential night and day temperature of 
about ioo°, until filled by the first Hood of the rainy season, so that it may he- 
supposed to have undergone the most severe trial to which a dam is liable. 




Reinforced Concrete Dam near Johannesburg. 



245 



RECENT BRITISH PATENTS. 



iCONCBETEj 



RECENT BRITISH PATENTS 
RELATING TO CONCRETE. 

We propose to present at intervals particulars of British Patents issued in connection 
ivith concrete and reinforced concrete. These particulars have been prepared for this 
Journal bv Mr. A. W. Farns'worth, of Strand Chambers, Derbv. The last article appeared 
in our issue of October, 1912. — ED. 



Improved Hollow Beam of Cement or Concrete and Apparatus for Making 
Same. — No. 22,196/12. F. Emmrich and U. Silbermann. Accepted January 9 13. — 
The principal points about this invention are the use of hollow supporting beams for 

JzT^ 1 





/.\ 



floors, having egg-shaped cores. Fig. 3 shows a 

section of beam adopted, e and / being ledges upon _r rg.l- 

which the flooring slabs are carried, k, k being 
wood insets on top and bottom for easy attachment 
of floor and ceiling materials. The hollow interior 
being egg-shaped it is claimed gives a much lighter 
beam than ordinary, since the construction allows 
of the walls being made thinner than is usually the 
case. Fig. 1 shows, in perspective, one type of 
floor for which these beams may be utilised. Fig. 
4 shows the metal core which is used for producing 
the hollow beams when moulding. It is made in 
upper and lower sections out of metal materials. 
The lower section (m) carries a series of small 
rollers (/>), and the upper section is hinged at o ; t 
is a girder running longitudinally through the core 
carrying strips (s) pivotly connected so that when, 
by means of screws, the girder (t) is moved length- 
wise in the core, the sides (n) of the casing are 
caused to come inwards, hinging around o. The 
upper portion of the mould thus falls down on to 
the rollers (/>), being guided by the L's (r) falling 
down the sloping sides (</). When in this manner 

the top half of the mould has fallen on to the rollers it is easilv pulled away and the 
bottom half (m) of the mould is then slightly lifted and withdrawn. 

Improved Arrangement of Constructional Steel or Ironwork or Reinforce- 
ment for Concrete and the Like.—Xo. 5,154/12. /. D. Roots, M.I.M.E. Accepted 
January 23/13. — With the object of providing a simpler and cheaper construction of metallic 
reinforcement for concrete, involving less time and labour in fitting same into position 
than other forms of reinforcemenl and yet be equal to most known methods in strength, 
the inventor u^s tapes or ribbons or bars of flal steel for connecting the main reinforc- 
ing members together. In Fig. 1 is shown a floor constructed on this method. B, />' 
are T-bars, into the webs and tables of which have been placed ^lot^ staggered relatively 
!o one another and at suitable distances or intervals in accordance with the load or 




y 



246 



r », CONSTDtJCTlCMAl.l 
1A ENfHISt-lLIJING~J 



RECENT BRITISH PATENTS 



stress on the door. Into these slots .-ire laced the steel ribbons, as shown ii 
that a continuous lacing effect is obtained as between the top and bottom main mci 
Various modifications are also shown and alternative methods of constru i, in. 




dueling the design as applied in the case of columns, pillars, etc. The inventor does 
not confine himself to main members composed of T-section only, but illustrates several 
other sections. 



Improvements in Reinforced Concrete Beams. — No. 15,889/12. /. T. McNay. 

Accepted January 9/13. — The inventor describes here a method of holding reinforcing 
bars more or less rigidly within the mould, so that when ramming of the concrete 



<•/ t f 



£ Xt 1 





^€€f. 2. 



13 then rammed with concrete, the 
oressed in the ordinary manner. 



material takes place these bars shall not be 
displaced or upset in their various relationships 
with each other. He explains that in the 
ordinary way, when reinforcing bars are not 
rigidly held in the mould, a great deal of time is 
wasted in setting and there is always the risk 
of the bars getting knocked out of position or 
being improperly placed in the concrete. The 
method is illustrated in Fig. 1 in the case of a 
longitudinal beam supported by columns. The 
ordinary centering is placed in position, as shown 
at b in Fig. 2; blocks (d) are placed on the top 
edges, and on these rest dropped bars (c) which 
carry the top reinforcement members (a 1 ). From 
these latter members looped bars (c3) are sus- 
pended for carrying the upper ends of the lx>ttom 
reinforcing members (a- and « ; ), their lengths 
being proportionate to the proper distances 
required for setting them in the mould. Fig. 1 
shows these looped bars in position. The mould 
centering afterwards knocked away and projections 



Improvements in Reinforced Concrete.— Ye. 11,962 12. D. G. Somervil 
Accepted January 23/13.— This deals with the twisted wire method of securinj 
reinforcing members together. It is stated thai by the use of this method it is 



2J 



RECENT BRITISH PATENTS. 



[CONCRETE] 



Ftg.t 




necessary for main members to be 

slotted di" specially shaped, since the 
wrapping of the wire round them 
causes the latter to grip them firmly 
when finally twisted together. An 
added advantage is stated to be. that 
subsidiary members can be added before 
the reinforcement is in situ, since the 
whole of the latter can be built up in 
the workshop or in any other con- 
venient place and then dropped into the 
mould as a whole. Thus such members cannot be displaced during the ramming of 
the concrete in the moulds, but they, and also the main reinforcement members, will be 
kept in their proper assigned place. Fig. 4 shows a diagram of the annealed mild steel 
wire used wrapped round four main steel members, the arrangement being such as to 
leave at least two parallel lengths of wire one on either side of the main members. 
These are then engaged by a tourniquet, or its equivalent, and twisted round one another 
until the desired tension and an effect like that illustrated in Fig. 1 are obtained. 
During this procedure the main members must be held immovable in a suitable frame- 
work. It is stated that after the withdrawal of the tourniquet the central eye, 4, may 
in some instances be pinned to the concrete, although generally the twisted wire will be 
-ecurelv anchored without this extra assistance. 



Improvements in and relat- 
ing to Consolidating Concrete 
within Moulds. — No. 3,248/12. 
H. C. Heide. Accepted February 
6/13. — The underlying idea of this 
invention is to obtain homogeneity 
in concrete constructions made in 
moulds. In. order to consolidate the 
concrete, the table or supporting 
platform upon which the moulds are 
placed for filling is pivotly mounted 
and is combined with means for 
imparting suddenly-arrested vertical 
rocking movements in intersecting 
vertical planes. Fig. 1 showsth table 
(g) supported upon a suitable frame- 
work and pivotly mounted on f. 
Fig. 2 shows a plan of the frame- 
work, and gearing is introduced so 
that tilting movements are imparted 
in such manner that each corner of 
the platform receives two or more 
blows jn quick succession. Various 
cams are used, so that the order of 
the blows or shakes may he varied 
a- desired. Figs. 3 and 4 show this. 
The specification describes the con- 
struction in detail. 




Fty. 4. 



Improvements in and relating to the Reinforcement of Concrete Structures. 
No. 5,872 12. J- S. F. /)<' Vesian. Accepted February (> 13. The object of this 
invention is to provide improved means of looping or binding longitudinally rein- 
forcing members wrapped with short lengths of spirally-wound metal. The helical 



248 



r j,. CON>TBUCTlONAL.l 
[Ci. ENGINEERING — J 



RECENT BRITISH PATENTS. 



windings are each provided with a com- 
plete loop ai each end with or without 
additional loops adapted to encircle 
other longitudinal rods. In the 
sketches a, <i are loops formed at the 
ends of the windings b, b, and the 
latter may be right- or left-handed 
helicals, or they may be right- and left- 
handed helieaN alternately disposed 
with or without a short interval be- 
tween the windings. Preferably the 
windings will be formed on a mandrel 
or template before use, and they would 
then be threaded on to the vertical bar.-. 

as soon as the bars are put into position. It is stated that, 
instead of long lengths, the members can be disposed and arr 
facilities than when long lengths of wire are used. 

R 





a> 



iMiiplo 
mgec 



ymg shot 

with inn 



t helicals 
h greater 




Improvements in or connected 
with Means Employed in the Con* 
si ruction of Barges or other Vessels 
of Reinforced Concrete and in 
Vessels Constructed of such material. 
— No. 2,138/12. N. K. Fougner. 
Accepted January 27/13. — Not very 
much progress has yet been made in 
the art of constructing reinforced con- 
crete barges or vessels, and this is a 
device designed to facilitate the build- 
ing of composite hulls without the great 
1 xpense which has hitherto attended 
experiments made in this direction. 
The principal feature of the invention 
is a special cradle, upon which the 
forms for receiving the concrete can be 
readily and cheaply laid. Fig. 1 shows 
this in part sectional elevation, and 
Fig. 3 in half-cross section with moulds 
in position. It will be seen that the. 
central idea is to provide a strong steel 
under-body furnished with a sufficient 
number of wheels which rest upon a 
railed platform. The rails are arranged 
sloping towards the water, and tin- 
cradle is held in position by a windlass 
and rope. When the barge is reach' for 
Launching, the windlass is operated mid 
the cradle nil's on its rollers into the 

water, where the hull floats off its 
supports. Thi' cradle is then hauled 
back again and re-building commences. 




?49 



RECENT BRITISH PATENTS. 



saiiEaii 




r£ s-~* 



The construction is shown in detail in the various drawings, and the operation of build- 
ing the hull upon the cradle is further described. 

Improvements in and re- 
lating to Moulds for Casting zo fl Flo J 
Concrete and Like Walls. — 

No. 11,072/12. W. M. Venables. 
Accepted January 30, 13. — This is 
an attempt to improve the assem- 
bling of wall moulds of the kind 
constituted by rows of abutting 
flanged plates. Fig. 1 shows 
these moulds in perspective eleva- 
tion, and it will be seen that 
square flanged plates are em- 
ployed, these being joined togeth< r 
by means of slots (8), through 
which pins and wedges, as shown 
in Figs. 2 and 3 are inserted. 
The walls are kept the right 
distance apart by means of dis- 
tance pieces, shown in Fig. 4, 
likewise held in position by wedge 
constructions. In order to obtain 
perfect alignment, flat strips (7) 
are inserted between the flanges 
of the plates, either vertically or 
horizontallv as may be required, 
and it is claimed that when this /y 

construction is made of light steel- 
work it is very readily erected, that it gives a good surface, that the plates are kept 
properlv in alignment, and that a good job is made. 

Improved Process for the !Wanu= 
faeture of Sleepers of Reinforced 
Concrete — No. 13,56;. G. H. Gin. 
Accepted January 16/13. — This inven- 
tion describes a process for the manu- 
facture of sleepers of reinforced con- 
crete, according to which the sleepers 
are composed by casting of wet or 
sloppy cement mortar pound in a 
special mould into which has previously 
been placed the reinforcements with or 
without metal fibre, and the spiral 
strips for reinforcing the screw-threads 
mounted on standard pattern coach 
screws. Fig. 2 shows the hydraulic 
press in which the sleepers are pro- 
duced, together with the mould for 
same in position. Fig. 3 shows the 
spiral strips used for reinforcing the 
screw-threads of the coach screws which 
are cast in position. The inventor 
describes the process of moulding at 
length, which is, briefly, that the mould 
is so composed that the top and bottom 
can slide vertically up and down within 
the side members, so thru when 

pressure is being applied and the water begins to How away from the sloppy cem< nl 
mortar, the sleeper may be broughl to the proper size as the bulk of the mortar gets 
less. After pressing, it is stated thai the sleepers are practically dry, and may be 
immediately removed from the mould and the process continued. 
2 ^o 



n%z 




1^5. 







r», CCN3tUUCT!ONAL| 
LGLEMOUNEE.mNCi — J 



RECENT BRITISH PATENTS. 



ri.ql 



hq2 



h 






4 



' y -f- 



32 













"-S 






-«-»t 



4 



vf 



fl.-; .■■?-"■■ -Sj 



Head for Reinforced Con- 
crete Piles. — No, i- / . y. 
Stulemeyer. Accepted January 
9/13.- The well-known diffi 
in driving concrefc 
out hurting their heads is 
dealt with by providing such 
piles with heads which are made 
of flexible material, similar to 
mortar and firmlv conn< 
with the body of the piles. 
<*■ Figs. 1 and 2 show thai this is 
attained by making the reinforcing bars (h) of the pile 
bod) longer than usual, so that they project. The line 
.4, B in Fig. 1 represents the end of the pile proper, 
the portion above the line being the capping material. 
Horizontal binders (/) may be employed in the cap similar 
to those in the body of the pile. In order that the head may 
be easily removed after driving, a separate layer, made of 
paper or similar material, is introduced on the surface A B. 
The head is then composed of a mixture either of cement 
and asbestos fibres or cement and saw-dust, or cement, 
saw-dust and magnesite or some other flexible mortar in which fibrous material such 
as hemp, cellulose, and the like may be employed. It is claimed that this construction 
saves considerable expense and has many advantages. 



CLOYD M. CHAPMAN. 



[CONCRETE 




CEMENT AND CONCRETE at 

the NATIONAL ASSOCIATION 

OF CEMENT USERS, U.S.A. 

TESTS OF WATERPROOFING FOR 
CONCRETE. 



By CLOYD M. CHAPMAN, 

Engineer in Charge, Westinghouse, Church, Kerr & Company, New York, N.Y. 

The following Paper <was read at the Ninth' Convention of the National Association o> 
Cement Users, U.S.A.— ED. 



So much that is contradictory has been said and written concerning various methods 
of producing concrete which is waterproofing, and so much has been claimed by the 
vendors of various compounds which have been offered to the public as a positive 
solution of all waterproofing problems, that it is not surprising' that not one cement 
user in ten has any definite or fixed opinion as to how to meet the problem of pro- 
ducing a waterproof concrete. There seem to be as many opinions on the subject as 
there are men willing to express their opinions. And the many methods which have 
been used differ greatly from eacn other. They are not all bad, for some of them have 
been very successfullv applied. They are not all good, for many failures have occurred. 

To throw more light upon the effectiveness of the various methods of waterproofing 
concrete a great many tests have been made by numerous investigators. The methods 
usk d by these experimenters have ranged from absorption tests to high-pressure tests 
necessitating more < r less elaborate apparatus. 

The absorption, or non-pressure, tests are made by preparing specimens of any 
; redetermined size and shape of the concrete waterproofed by the particular methods 
under investigation. After the desired age is attained, the-.;- specimens are either 
immersed in water completely or immersed almost completely, or placed in shallow 
water so that the bottom only oi the specimen is wet; or the specimen may be made 
cup-shaped, so that the water may be placed in the depression in the specimen, or a 
container for the wan r may be attached to the surface of the specimen. 

In all these forms of tests the results are expressed in terms of the amount of water 
absorbed or the rate of absorption. 

In the pressure te>ts the specimen is either so made that the water-pressure may 
be applied to the interior of the test piece, or it is so made that it may he inserted in 
the apparatus in such a manner that the water-pressure may he applied to a certain 
area on one face i |" the tesl piece. In this form of test the results are expressed in 
teims of the amount of water passing through the specimen or the rate of flow 
through it. 

I' th the above h-is are very valuable if carried out in such a manner that the 

r< suits may reasonably be expected to compare with results which may be obtained in 

practical work. To this end it is desirable that certain precautions be observed in 

preparing specimens ar.d conducting tests, so that the results shall not be misleading 

ir deceh ing. 



IF 



tJg MSMJMio^ WATERPROOFING CONCRETE. 



It is the purpose of this paper to call attention to some of the features oi 
this class and to emphasise more strongly certain precautions, failure to ol 'hich 

may cause some of these tests to give very deceptive data. These precautions apply 
particularly to tests made for the purpose of determining what method shall i>. 
on a particular piece of work in the field. Some of them do nol apply to tests d< - 
onlv to compare the relative efficiency of various meth ds, without regard to anj par- 
ticular work at hand. 

First : The selection of the materials to he used in making up the tesl pieces. I hese 
should be selected from those available at the site of the work which is to be dime 
This is particularly true of the fine and coarse aggregates. It has more than ona 
happened that tests made with suitable aggregates have shown a particular method 
to give a waterproof concrete, but the same treatment failed when the aggregates 
available in the field were used. If, therefore, it is desired to determine by test how 
to produce a waterproof concrete for a particular job, the materials available at the job 
should be used in making up the test pieces. It is also important, in connection with 
the selection of aggregates, that there be secured a sufficient quantity of the materials 
to be used to conduct the entire line of tests contemplated, so that there need be no 
change in the materials used. 

Second : The proportioning of the materials : This should be done with a view to 
determining the proportions to be used later on the work. The proportions to be used 
in the tests : There is little use in testing only a i : 2 : 4 concrete for watertightness, 
and then use 1 : 2\ : 5 on the job. 

Third: The mixing of the materials. This should duplicate as nearly as possible 
the mixing to be used on the work. Many a well-mixed concrete has proven water- 
proof which would have failed utterly if carelessly mixed. There is a tendency to verv 
thoroughly mix concrete for a test, and then make no special provision for thorough 
mixing on the job. 

Fourth : The consistency of the mixture. This should be carefullv considered 
because of its influence upon the results. A consistency should be chosen which it is 
practical to use on the job under the circumstances prevailing there. For instance, it 
is useless to test a concrete of so thick a consistency that it would have to be spaded 
into the forms if, on the job, the concrete is. to be spouted from the elevator, and, 
therefore, necessarily of a much thinner consistency than was used in the test. 

Fifth : The moulding of the test specimen. This process should imitate as nearly 
as possible the filling of the forms as it will be done on the job. To make a test piece 
by putting into the mould a small quantity of concrete at a time, and constantly tamping 
during the filling process, would probably produce a deceiving result. 

Sixth : The finishing of the surface to be tested. This is one of the most important 
points in the preparation of test specimens. The condition in which that surface which 
is to be subjected to water is left has a very great influence upon the results obtained. 
For instance, it is quite possible, by means of a little trowelling, to produce a skin, or 
surface coating, of nearly neat cement. This will produce a dense surface much more 
impermeable than the body of the concrete, and show results far superior to an 
untrow elled specimen of the same concrete. It is recommended that specimens be so 
prepared that the surface expose'.! to test truly represent the body of the concrete. This 
may be accomplished by removing the surface ky{ the specimen after the concrete has 
hardened bv means of a wire brush or by chipping or breaking off the surface before 
test. 

In the case of absorption tests this may lie done with a stiff wire brush when 'he 
specimen is about twenty-four hours old. In the case of the pressure t<- : -. only that 
portion of the surface which is to be subjected to the pressure and that portion 

n 



CLOYD M. CHAPMAN. [CONCRETE] 

which the water passes out of the specimen need to be removed. This may be accom- 
plished bv making the test piece with additional material added to the surfaces to be 
tested, so that this additional concrete may be broken off after the specimen has 
hardened and before the test is performed. Unless some such precaution is taken, 
tests of this character are liable to show the efficiency of the surface of the specimen 
in resisting the water-pressure rather than the value of the mass of the concrete in 
performing the same function. 

One suitable form for a specimen for pressure tests is shown in the accompanying 
illustration. It is in the form of a central disc, a, of suitable diameter and thickness. 




The outside surface and the outer portion of the two faces of this disc are moulded 
smooth and regular, so as to fit the receptacle or holder into which it must be placed, 
in order to apply the water-pressure to a definite and restricted area of its surface. 
From the central portion of the two faces of this disc project truncated cones, bh, whose 
smaller diameter is just equal to the diameter of the circle which is to receive the water- 
pressure. After the specimen has hardened and is ready for test, the two truncated 
cones are broken off with a blow of a hammer, leaving a disc such as is shown 
at c. 

Bv this method there is exposed to the water-pressure a freshly broken surface of 
concrete which has not been subjected to trowelling or other influences tending to alter 
the natural condition or distribution of the constituents of the concrete. This freshly 
broken surface is not only presented to the water on the side to which the pressure 
is applied, but is also provided on the opposite side where the water leaves the 
specimen. The test, therefore, is made on a certain thickness of concrete taken from 
the interior of the specimen, and the results are not influenced bv the method of 
finishing these two surfaces. 

There are, of course, cases in which it is the surface permeability that it is desired 
to test, and in such cases this form of specimen is unsuitable. But in all cases' in 
which the watertightness of the concrete mass is to be determined the above type of 
specimen is much to be preferred. 

There are also variations of this form of test piece which will accomplish the same 
result. Any method which removes the finished surface from the area to be tested is to 
be preferred to one which does not remove that surface. 

Even in such cases as those in which the specimen is moulded on a surface of 
"lass or other smooth material and no trowelling is done, there is a concentration of 
cement and fine aggregates next to the surface which must affect the results obtained 
if this richer laver or skin is not removed before test. 

Seventh : The curing or ageing of the specimen. This matter should also be decided 
with a view to conditions which will prevail in the field when the real work is done. 
If it is impracticable on the job to keep the Loncrete constantly wet for a considerable 
period, then the tesl specimens should not be stored in water. If the only wetting the 
work in the field is to receive is the water contained in the concrete when it is placed, 
then the test pieces should receive no additional water after moulding. On the other 
hand, they should not be allowed to dry out any faster than would the work in the 

*5 + 



ggjjllilg WATERPROOFING CONCRETE. 



field, as they would doubtless do owing to th.'ir comparatively small size if kepi indoors 
in a laboratory and no precautions taken to regulate the drying process. 

The specimens have now reached the stage when they arc ready for w 
bests are to be applied to them, and the methods used in performing these t< 
so varied that the limited scope of this paper will not permit an extended discussion of 
them. Those with which the writer is familiar appear to be open to little, if any 
criticism. One of the most important feature-, is that the conditions adopted shall 
remain constant throughout the test. 

If the test is an absorption or a non-pressure test the immersion or partial immer- 
sion should be under uniform conditions and for definite lengths of time in clean water. 
If the test is a pressure test, the pressure should be kept constant, the water clean, and 
the method of measuring the water passing through the concrete accurate. As the area 
subjected to pressure is usually small, the amount of water passing is correspondingly 
small, and in some cases where the measurement of the water is made by collecting the 
drippings from the underside of the test piece the element of evaporation may greath 
affect the results. A form of apparatus in which the amount of water passing 
into the specimen is determined eliminates this error. 

In this form of apparatus the specimen is clamped and sealed to a metal cap which 
is provided with a projecting vertical graduated glass tube. The cap and the tube are 
filled with water and air-pressure is then applied to the top of the tube in any desired 
amount. As soon as the specimen has become saturated and water begins to flow from 
its exposed face a reading is taken of the water in a graduated glass tube, and there- 
after readings are taken at regular intervals of time during the period of the test. If 
it is necessary to introduce more water into the system when testing porous concretes, 
this may be done by opening an inlet which is supplied with water at a higher pressure 
than that of the air in the tube and so filling the glass tube again up to the zero mark. 

By this method accurate determinations may be made of the amount of water 
forced into a concrete which is so near waterproof that all, or a great part, of the water 
which passes through it would be evaporated from the exposed surface. 

Another matter in connection with tests of waterproofings for concrete which seems 
to have had but little attention paid to it is the effect of time and the elements upon 
efficiency of the waterproofing materials. In practically all of the numerous tests of 
waterproofing made in the past seven or eight years in the laboratory of Westin^house, 
Church, Kerr & Company, it has been the custom to expose the test pieces to the 
action of the weather on the roof of their office building after first testing them, and 
then testing again after six or twelve months' exposure. The results of these tests after 
prolonged exposure show that few, if any, of the materials which are applied to the 
surface of concrete to waterproof it after it is made will retain even a fair proportion of 
their efficiency. In the case of those methods by means of which the entire mass of the 
concrete is designed to be waterproof, there is shown sometimes a steady improvement 
after exposure and sometimes a marked decline. In some cases the life of the treat- 
ment is very short and the failure after a few months' exposure almost complete. 

It is important, therefore, before any particular method of waterproofing be 
adopted, that the probable life of the treatment be ascertained. It is pretty well estab- 
lished that a ^ood concrete without foreign substances in it improves with age, becomes 
more dense and watertight, but the same cannot be -aid as positively of a concrete 
containing some of the recently developed compounds intended for waterproofing. 



2 55 



DR. CECIL H. DESCH. 



[CONCRE TE 




THE WORK OF THE GROSS-LICHTERFELDE 
TESTING STATION. 

The following article on the Gross-Lichterfelde Testing Station, Berlin, should be oy 
interest to those of our readers "who follow the research work carried on in different countries, 
as this testing station undoubtedly takes a very high rank among our scientific institutions. 
This article has been prepared for us by Dr. Cecil H. Desch, of the Glasgow University, 
and Professor Martens, Director of the Testing Station, kindly placed the illustrations 
at our disposal.— ED, 



Generally. — The report of the Royal Station for the Testing of Materials at 
Gross-Liehterfelde, near Berlin, has now been published for the year ending March 
31st, 191 2, and affords a convenient opportunity for considering the nature and 
extent of the work carried on in this celebrated institution. The six depart- 
ments of which the Station consists have come into being at different times 
between 1871 and 1886 to meet the needs of the Charlottenburg Technical 
School, the Berlin Academy of Mines, and of various public departments and 
associations of manufacturers. The accommodation provided at Charlottenburg 
from 1884 onwards proving insufficient, a new Institute was erected at Gross- 
Lichterfelde, and was opened in 1904. 

Our illustrations, Figs. 1 and 2, show the vast size of the building, which 
is situated between the main road and the railway, on the way from Berlin to 
Potsdam. The site secured is of ample dimensions, to allow of future growth, 
and also to provide sufficient space for open-air tests and for temporary erec- 
tions. The equipment is admirably complete, and the handsome " Denkschrift " 
published on the occasion of the opening, and giving full details of buildings, 
plant, and apparatus, should serve as a standard work of reference on the 
important subject of the equipment of laboratories for the testing of materials. 

The staff of the Testing Station was composed in 191 1 of 227 persons, no 
less than 74 of whom had received a University training. The director is 
Prof. A. Martens, whilst the sub-directors and chief assistants include such 
well-known names as those of Professors Rudeloff, Gary, Hem, and Burchartz, 
the connection with the teaching staff of the Charlottenburg Technical School 
having been maintained since the transfer to the new site. 

256 



I 



T CONSTRUCTIONAL 
ENGITMfcfcKlNCi — , 



GROSS-UCHTERFELDE TESTING STA 7VO.Y. 



EXPLANATION OF LETTERS ON BLOCK 

A — Principal Building. 



B v — West Testing Rooms. 

B L — West Laboratory Building. 

M v — East Testing Rooms. 

M L Mast Laboratory Bui'ding. 



W— Workshop. 

C — Engine House. 

D — Accumulator Building. 

SR — Cooling Towei . 

F — Fire Laboratory. 

K — Boiler House 




Fig 2. Plan. 
Gross-Lichterfei.de Testing Station, Berlin. 



The following are stated by the director to be the principal objects of the 
Testing Station : — 

(a) The improvement of methods, machines, instruments and apparatus 
employed in testing-, in the public interest. 

(b) The testing of materials and structural members : — 

i. In the interests of the public or of science, so far as the means 
are provided by the State or by private persons. 

2. At the request of public bodies or private persons, against the 
payment of a fee, official certificates being granted. 

(c) At the request of both parties to decide in cases of dispute as to the 
strength or quality of materials or structural members. 

Further, as far as the interests of the institution permit : — 

(d) Instruction of students in the Technical High School and the train- 
ing of young assistants in the practice of testing. 

(e) The encouragement of research in certain special departmen 
allowing the use of the equipment by outside investigators. 

The work of the Testing Station is distributed over six depai 



DR. CECIL H. DESCH. 



EQNC BETE] 



namely, metals, building- materials, paper, metallography, general chemistry, 
and oils. Of these, the second is naturally of principal interest to the readers 
of this journal, but the first also includes much work of importance to the 
constructional engineer. 




I he departmenl for the testing of building materials occupies the ground 
floor of the western wing, together with special rooms in other parts of the 
building and huts, etc., on the surrounding ground. Th 

shows the principal testing room 
2-8 



..round. I lie photograph, Fig. 3, 
tins department, provided with four com- 



I 



, CONSTKUCTlONAlJj 



GROSS-LICIITXRI-KLDE TESTING STATION. 



pression machines, of 400, 150, 40, and 33 tons capacity respe 

as 5- and 2-ton presses for transverse tests. All these presses i r drau 

action, and the loads are read by means of pressure gauges. I h 

contains the machines for testing cement briquettes in tension, and Gary's 




apparatus for determining- the permeability of mortar and concrete to w a 
The great 500-ton horizontal testing machine shown in Fig. 4 belongs I 
section, that of metallic materials, but it is also used for bending and - 
tests on reinforced concrete columns and similar purposes. Sucl objec 

259 



DR. CECIL II. DESCH. 



[CO NCRETE] 




o *-? 



260 



KengSSi^ GROSS-L1CHTERFELDE TESTING STATION. 

reinforced concrete pipes are also tested by means of ma< nines 
properly to the metal section. Our photograph, Fig. '>, shows the tower 
which falling" weight experiments are carried out. The department i 
amply provided with equipment for chemical analyses, for the making 

storage of cement and concrete test-pieces, and for special tests of the resistana 
of materials to weather, frost, chemical fumes, etc. To another subject — the 
fireproof qualities of materials — further reference is made below. Fig. 5 shows 
the great 3,000-ton machine which has been recently installed. This enormous 
press — by far the largest in Europe — has been erected at the request of the 
Union of German Bridge and Structural Steel Firms by Messrs. Haniel & Lueg, 
of Diisseldorf. It can take entire girders, struts, columns, and built-up bridge 
sections, in compression or tension. 

The extent of the work of the building materials section may be judged by 
the following facts taken from the report for 1911-12. The total number of 
applications was 1,023, involving 39,000 experiments, of which about one-half 
dealt with cements of different kinds. 

Cement. — The tests with Portland cement and blast-furnace slag cement 
(" Iron-Portland ") showed a steady improvement in quality since the raising 
of the German official standard. One cement showed, in a 1 : 3 normal mortar, 
after seven days under water, a tensile strength of 35T kg. /'cm. 2 (499 lb. in.-) 
and a compressive strength of 460 kg. /cm. 2 (6,541 lb. /in. 2 ). The same mortar, 
after 28 days in water and air, gave a tensile strength of 48*7 kg. /cm. 2 
(692 lb. in. 2 ) and a compressive strength of 692 kg. /cm. 2 (9,840 lb. /in. 2 ), the 
highest value yet recorded in this laboratory. 

The opinion was given, in answer to a special demand, that the spontaneous 
change of a slow-setting to a quick-setting cement was not to be regarded as an 
indication of inferior quality, as such spontaneous changes take place with 
changes of temperature even in good cements. Petroleum and other oils were 
found to weaken cement mortars very considerably when the latter were 
exposed to their action after 28 days hardening in air. The injurious influence 
is greatest in lean mixtures. Experiments were also made to test the question 
whether reinforced concrete could be safely employed for shafts and buildings 
exposed to the action of waters (potash salt liquors) containing magnesium 
chloride. It was found that such salts always attack cement. The addition of 
a " frost-protecting " substance to concrete during mixing has been recom- 
mended, and tests with such a concrete showed that if exposed to air for one 
day and then alternately frozen and thawed twenty-five times, no external 
change was produced, but that the resistance of reinforcing rods to slipping 
was seriously reduced by the addition of the protective material. 

A frequent request is to determine the proportions originally used in 
mixing a concrete, from an examination of the hardened material. This is, 
except in the simplest cases, an operation of considerable difficulty. It is pos- 
sible to determine the proportion of cement, if used alone, and in certain 1 
to decide whether an addition of either fat or hydraulic lime has been made to the 
cement, but it was not found possible to decide whether the breeze used in a 
certain breeze concrete was satisfactory or not. There is undoubtedly 
for improvement in this class of testing, which i.^ so important in disputed 

The concrete pipes used for the conveyance of water in a cer! tin district 
showed corrosion after one year in the soil, amounting to di n of one- 



DR- CECIL H. DESCH. 



fCQNCRE rE) 



third of the pipes over a length of 300 metres. In this case it was not found 
possible to determine the cause of the corrosion. The soil did not contain 
acids or other destructive substances. The material of the pipes did not appear 
to have been well mixed, but a definite conclusion was not reached. 

A number of scientific investigations were also proceeded with, the results 
of which have been published or are in course of publication. 

Fire Tests. — The tests as to the fire-resisting qualities of materials during 
the year were not very extensive, being limited to some " fireproof " doors, a hut 
of slag-stone, a comparison of a brickwork wall with one of sand-lime bricks, and 
one of an ordinary lime floor with a plaster floor. The provision for this branch of 
testing is inadequate, and compares unfavourably with the arrangements of the 
British Fire Prevention Committee. It is stated that it is proposed to extend 
this branch of the activities of the institution after an examination of the 
methods adopted by kindred institutions in London, New York, Chicago. 

Conclusion. — The services which a fully-equipped testing station of this kind 
are capable of rendering to industry are obvious. The publications of the Gross- 
Lichterfelde Station form a most valuable source of reference for all who are 
interested in such a department of industry as that of concrete construction, apart 
from the direct utilisation of the services of the station by German manufacturers, 
engineers, and building clients. We must not forget, also, the advances in 
methods of testing which we owe to Profs. Martens, Gary and their colleagues. 
Some of their methods have not been adopted in this country, and differences 
of opinion exist as to their value in comparison with methods due to other 
workers, but their share in developing the technique of testing is recognised 
and gratefully acknowledged by all who have followed the progress of 
structural materials in recent vears. 



Wflf 






u 



m.m 






i ***«*? 



262 



Fig. 6. Tower for Falling Weight Experiments. 

GrOSS-I.ICHTERI-ELDE TESTING STATION, BERLIN. 



fk 



I 



CONSTRUCTIONAL! 
ENGTNEEKlNG^-3 



SETTLEMENT OF SOLIDS, ETC., ON CONCRETE. 




RECENT VIEWS ON 
CONCRETE AND REIN. 
FORCED CONCRETE. / 



THE CONCRETE INSTITUTE. 



It is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
in such a manner as to be easily available tor reference purposes. 

The method ■we are adopting, of dividing the subjects into sections, is, ive believe, a 
neiv departure. — ED. 

THE CONCRETE INSTITUTE. 

THE SETTLEMENT OF SOLIDS IN WATER AND ITS 
BEARING ON CONCRETE WORK. 

By DR. J. S. OWENS, Assoc.M.Inst.C.E., M.R.San. I., F.G.S. 

The following is an extract from the Paper read before the Institute at their Thirty-first 
Ordinary General Meeting. A sliort resume of the discussion is also given. 

INTRODUCTION. 

The Lecturer, in opening, stated that it would only be possible to give a brief outline 
of the subject under review, and referred his audience to papers read by him before the 
Royal Geographical Society, Research Department (see Geographical Journals, Janu- 
ary, 1911, and March, 1912); before the British Association in Dundee last September 
(see Engineering, December 20th last); and a paper before the Society of Engineers of 
March 1st, 1909. 

He proposed to deal with some of the physical characteristics of stones or shingle, 
sand and mud, which lead to their separation into these distinct classes by nature. 
Practically all the sorting is done by the agency of flowing water, and the chief factor 
governing the position of any deposit is the ability, or otherwise, of the water to hold 
the material in suspension. Very finely divided matter remains long suspended, and 
therefore, if in a current, passes over the place where coarser matter is being deposited, 
and settles in less disturbed water. 

With the exception to be referred to later, a heavy solid can only be supported in 
suspension in water by an upward thrust equal in intensity to that which would result 
from a current of water of the same velocity as the body would settle at in still water. 
This means : (a) it is to the resultant upward thrust due to eddies and disturbances 
that suspension in water is due ; and : (b) a measure of the rate of fall of a body through 
water will be useful as measuring its resistance to suspension. 

A solid body which is of higher specific gravity than water will sink in the latter 
at a definite rate. Starting from rest, it will have two distinct stages in its fall :— 

1. An accelerating stage during which the force operating on the body to pull it down is 
greater than the retarding force due to friction and the impact of the water particles 
on the under surface of the body. 

2. A stage of uniform motion which is attained when there is an equilibrium between the 
downward and upward acting forces. 

In practical work tin- first or accelerating stage is so very short as to be negligible, 
except for very large be dies. 

The chief' factors governing the rat.' at which a body will settle through water are : 

(1) its size, (2) shape, (3) specific gravity, (4) the temperature of the water, or any cause 

affecting the viscosity of the liquid, (5) the quantity of suspended matter pn 

water. 

26} 



THE CONCRETE INSTITUTE. (CONCRETE] 



SIZE. 



If v represents velocity of fall in foot seconds, d diameter of body in feet, s specific 
gravity of body, and fe a constant depending on the shape of the body (equal to about 
9'35 f° r spheres, 6" 12 for irregular grains of sand, according to the author's latest 
experiments), the velocity of fall in water for bodies over T \j of an inch in diameter 
will be given with fair accuracy by the expression : — 



v = l^ d(s-i\ 
It will thus be seen that the rate of fall varies directly as the square root of the 
diameter. 

SHAPE OF BODY. 

The author found that a curious law governs the position a body of irregular shape 
takes up in falling through water. It is the custom to apply the law of " least 
resistance " to explain many phenomena in nature. If applied in the present case, it 
would seem to indicate that a body such as a disc will settle through water edgewise, 
a rod endwise, and so on ; but the contrary is the case : a disc always settles on the 
Hat, a rod with its greatest length horizontal. For this reason a sphere settles more 
rapidly than anv other shape, and flat, thin bodies, such as slates, settle very slowly 
3rdeed. 

SPECIFIC GRAVITY. 

Referring to the formula given above, it will be seen that the velocity of settle- 
ment varies directly as the square root of the specific gravity of the body minus that of 
the liquid in which it settles. In the case of two balls the rates of fall of which were 
measured bv the author, one was a composition ball having a specific gravity of rig, 
a diameter of -415 in., and a rate settlement of 794 f.s. ; the other a steel ball, 
specific gravity of 777, diameter "498 in., and a rate of fal l of 4- 96 f.s. If these two 
be compared, the velocities of fall should vary nearly as v '_s — 1, the diameters being 

approximately equal, that is rr- should be equal to == and it will be found that 

this is practically the case. 

WATER TEMPERATURE. 

This has a profound effect on the rate of fall of fine matter in water, due, no 
doubt, to its influence on viscosity. A rise in temperature of the water produces an 
Increased rapidity of settlement which is most marked with the more finely divided 
materials. The rate of settlement of silicious sand of TT f CTT in. diameter is doubled if 
the temperature be raised So° F. 

AMOUNT OF SUSPENDED MATTER PRESENT. 

It can be shown experimentally that the greater the load of suspended matter, the 
slower its rate of settlement. Finely divided solid matter held in suspension in water 
has practically the same effect on the specific gravity of the mixture, measured by a 
floating hydrometer, as if it were in solution. In order to bring out this point, he had 
made the" following experiment : Weighed quantities of whiting were mixed with 
similar volumes of water, and the specific gravity taken with a hydrometer. It was 
also calculated, assuming that the whiting had gone into solution instead of being 
suspended, and the figures obtained in each case compared. The results showed that 
the effect on the specific gravity of the mixture was the same whether the added matter 
went into solution or suspension. 

It is reasonable under the circumstances to suspect that the amount of heavy 
matter suspended in a liquid will influence its rate of settlement in the same way as 
.in alteration in the specific gravity of the liquid itself; and this is found to be the case. 

PRACTICAL APPLICATION OF RESULTS. 

It may first be considered how to define the meaning of the words "stone" or 
' shingle," " sand," and " mud." It is obvious that .any definition to be of use must 
he based directly or indirectly upon size of grain. 

264 



fc%3£8££S^] SETTLEMENT OF SOLIDS, ETC., ON CONCRETE. 

There appear to be two distinct sizes of particle to which further attention musl be 
given. It will be observed that the application of the formula given i 
be limited to sizes over ,' ( , in, diameter. The reason for this is as follows : [n experi- 
menting on the rate of settlement of differenl grades of material, it was found that 
the value of k in the formula referred to was fairly constant over ,',, in. diann U r; but 
for grains of smaller size it fell off rapidly in value', thus showing that some fai r'was 
operating in the smaller grades which was not taken into accounit in the expr< 
given. That this factor was the viscosity of the liquid he had no doubt, and its 
preponderating effect in the smaller grades may be due to the rapid increase in the 
ratio of surface to volume or weight, as the .size is reduced, or to the passing of a 
critical point in the velocity such as that shown by Osborh Reynolds to divide stream- 
line flow from eddying- flow-. 

While it is not strictly correct to speak of a critical diameter at which this effect 
commences to appear, it was found on plotting values of the constant k referred to 
that at about T ' l7 in. diameter the curve bent rapidly downwards, whereas above this 
i. was practically horizontal. 

There is possibly a second critical size of particle which is of interest if not of 
great practical importance. 

The chief retarding forces operating to prevent settlement of a body in water may 
be regarded as : — 

i. The upward impact of the water due to the velocity of fall of the body. 

2. Friction, the force necessary to overcome the viscosity of the liquid. 

When there is no velocity of fall (i) disappears, but some of (2) probably remains. 
As we reduce the size of the body the downward acting force, due to its weight, becomes 
smaller more rapidly than the frictional resistance, since the former varies as the cube, 
the latter as the square of the diameter. Hence it would seem that when the diameter 
is reduced to a certain critical value, the force operating to pull the body down will 
become equal to the frictional resistance to movement, and permanent suspension in 
the liquid result. As, however, there is probably no such thing on the earth as 
absolutely quiescent water, permanent suspension will result long before this critical 
size is reached, owing to movements in the water due to temperature changes or other 
causes. The blue colour of the sea has been attributed to the presence of fine suspended 
matter. 

Again, mud particles sometimes approach in size the limits of microscopic vision; 
so that we have clearly a considerable range of size to choose from in defining mud as 
distinct from sand. If we decided to take all below the critical diameter referred to 
as being mud, we have to consider how it is that particles of such a size as to be 
permanently suspended in water ever reach the bottom to form mud. 

A sample of yellow marl examined by the author for the purpose of this paper 
contained particles down to about .j^J^ of an in. in diameter, and the finest of these 
settled through water, although at a very slow rate ; for example, a glass vessel con- 
taining a column of about 12 in. of water in which a little of this clay was shaken up 
had not cleared after forty-eight hours in a temperature of 50 F., and after sixteen 
hours the water was still quite cloudy with grains about ao^wtr in. diameter. It is 
obvious, therefore, that the critical diameter for this was under stttttfu of an inch. 

CONCRETE WORK UNDER WATER. 

When concrete is allowed to settle through water, the effect is to bring about an 
analysis into coarse and fine strata. The larger particles — stones, gravel, etc. — settle 
more rapidly than the finer sand and cement; with the result that they reach the 
bottom first and form a layer over which the sand and cement settle, also in separate 
strata — the cement on top, the sand underneath it. The separation is not quite 
complete, because the large particles always carry down in their wake some of the 
smaller, and for other reasons which it is not necessary to refer to here. Even when 
allowed to fall through only a foot or so of water, the line cement is washed out and, 
to a great extent, remains suspended, owing to the disturbance of the water. 

EXCESS OF WATER IN CONCRETE. 

When line and coarse particles are suspended in a liquid the coarse, by virtue of 
their greater weight compared with their surface, tend to work towards the ' •torn. 

26,- 



THE CONCRETE INSTITUTE. 



[^CBETFl 



displacing the fine matter upwards; for it must be remembered that a body falling 
through a liquid always generates an upward current to fill the space which it occupied, 
and this is sufficient to keep very fine particles suspended. The case of immediate 
interest is that of concrete mixed with too much water; when kept in a state of 
disturbance by ramming there is a tendency for the coarse part of the aggregate to 
work towards the bottom, the finer sand and cement towards the tup giving a deceptive 
appearance to the concrete of having been thoroughly consolidated. 

CONCRETE MIXING 

It is not uncommon to meet with a so-called concrete mixer which, when closelv 
watched, is found in some cases to separate the fine from the coarse parts of the aggre- 
gate. It is easy to s< e from the earlier remarks made that with sufficiently liquid 
concrete a badly designed mixer may produce sufficient agitation to suspend the sand 
and cement, but not the coarser part of the aggregate, which consequently gradually 
separates out as a bottom layer. Of the two chief types of mixer now in use, one 
depends on revolving arms operating in a fixed vessel, and this is the type most likely 
to be affected by the cause described, unless very carefully designed with proper pro- 
vision for a positive mingling of the different parts of the concrete, as distinct from 
mere agitation. The other type, in which mixing is effected in a revolving vessel 
fitted with shelves, is more likely to produce good concrete, as its action depends on 
repeated shifting of parts of the mass from one place to another — for example, from 
b( ttom to top and sides to middle. 

TEST OF CONCRETE MIXING. 

The author was strongly of opinion that sufficient attention has not been given 
to the proper mixing of concrete. It is a process which has a perfectly definite point 
of completion, which is, however, not always attained to. Concrete may be said to 
be thoroughly mixed when all the ingredients are as uniformly distributed as possible 
throughout the mass. If this is accepted as a definition of proper mixing, then samples 
taken from different parts of a heap of concrete should contain the same proportion of 
stone, sand, and cement. The different rates of settlement of these three afford the 
engineer a simple method of measuring the relative proportions in any part of a heap 
of concrete. If, for instance, a small quantity of concrete be placed in a tall glass 
vessel full of water, shaken up, and allowed to settle, three distinct layers of sediment 
are formed. The stones or gravel settle immediately, then follows the sand, and after 
a much longer period — about ten minutes in a vessel twelve inches high — the cement 
forms another well-defined layer. The depth of these layers varies as the amount of 
the respective materials present ; hence, a simple measurement of the depths in two 
samples enables us to compare the relative quantities of the different ingredients at 
any two parts of the heap. 

In practice the application of this test may be simplified thus : Excluding the case 
of concrete, which is semi-liquid, and in which the coarse matter may therefore have 
separated from the fine, it may safely be assumed that if the sand and cement be 
properly mixed the coarser parts will be also mixed; since the time required to mix 
uniformly increases as the grain becomes finer. 

INSPECTION AS TEST OF MIXING. 

Two special tests have been made, to which attention should be drawn. The first 
was directed towards determining what was the true value of inspection alone as a 
test of concrete mixing. For this purpose a sample <>f mortar of the proportions 
lenient i, sand 2, was made; beside this was placed another having cement i, sand 2\, 
but no difference could be detected by eye. The result was the same with cement i, 
sand 3, and it was only with cement i, sand 3^, that any difference in appearance could 
with certainty be detected. On applying the sedimentation test to these samples the 
difference in strength beitween 1 in 2 and 1 in 2A was easily observed. It is therefore 
quite clear that inspection alone — the test which is ordinarily applied — is not sufficient 
to determine whether concrete is properly mixed or not. 

HAND- MIXING. 

The second test was one of hand-mixed concrete, turned twice dry, twice wet, on 
,-. London works of a reputable contractor. 

266 



[jjlllijlgg SETTLEMENT OF SOLIDS, ETC., ON CONCRETE. 

Seven tests were made of different batches, and uniformity found in one only. 
Thi following figures show the percentage variation in the amount of cement in different 
nnrts of each batch : — 



Batch No. i 

, , No. 2 
No. 3 

,, No. 4 

,. No. 5 

„ No. 6 

No. 7 



Per Cent. 



24 



17 

All batches, except No. 5, were mixed in the author's presence, or that of the 
foreman or engineer. No. 5 was mixed by the men alone, without supervision. It 
would therefore seem that when concrete is mixed by hand it may not be of uniform 
strength, and that to bring the weakest parts up to the strength required an excess of 
concrete must be used equal to at least 10 per cent, more than if uniformity of mixing 
could be assured. Turning twice dry and twice wet is not considered sufficient by 
most engineers to give a proper mix. On the other hand, as in the case referred 
to, this amount of mixing was permitted, relying upon the handling which the 
concrete subsequently received while filling into skips and placing in the work 
to complete the mixing. There is, however, a fallacy hidden here, because concrete 
is mixed in fairly large batches, whereas it is deposited very often in barrow- 
loads; this results in good mixing of each barrow-load, but not in any certainty 
that the proportions in all the barrows will be the same, since the concrete may be 
taken from different parts of an improperly mixed heap. It is hardly necessary to say 
that on even a small work using, say, one thousand tons of cement, a saving of 10 per 
cent, of this would be well worth making. By the use of a proper mixing machine, 
effectively used, this saving can be made. It is not impossible to get uniformity bv 
hand-mixing, but the amount of supervision required makes it practically impossible. 

Mixing machines vary greatly in their ability to mix, and also require supervision 
in their working as well as hand-mixing. 

The author showed an indicator, which was designed bv him for use with 
batch concrete mixers, and is intended to indicate to' the attendant when the mixing 
operation is complete. It consists of a modified revolution counter, in which a worm 
and worm wheel operate an index which shows on a dial revolutions of mixing drum 
01 paddles. The cycle of operations is as follows : — 

1. On opening the charging gate of a machine to admit a batch, the index drops to zero. 

2. When the batch is in the machine, the closing of the charging gate causes the index to 
commence revolving round the dial. 

3. When the index has reached a predetermined point (at which for convenience a movable 
pointer may be clampedl the batch may be discharged. 

4. An independent counter registers the number of batches mixed. 



The President, before the opening of the discussion, read two letters from members who 
were unable to attend. 

Extract from letter from Mr. Alban H. Scott, U.S.A., Member of Council C.l. 

" The paper contains a great deal of useful information, much of which confirms a test 
which I have previously carried out on similar lines. 

" Regarding the author's definition of the words ' stone ' or ' shingle,' ' sand ' and c mud,' 
in the first place such terms may be applicable and useful from a geological point of view, 
but when the subject is being considered under the heading of ' Practical Application,' such 
terms may be most misleading, as in the actual work these terms are bound to be used by all 
classes from navvies up to consultants, and the three definite words, ' stone,' 'shingle ' and 
' mud ' are open to very great misunderstandings between the various grades of men employed 
on the work. 

"The author defines that 'grains over i-ioth in. dia.' should rank as 'shingle,' while 
grains finer than this would rank as 'sand.' In the R.I.B.A. Report on Reinforced Concrete 
' sand ' is defined to a certain extent, and it is taken up to a material which will pass | 
of an in. mesh. 

267 



THE CONCRETE INSTITUTE. (CONCR ETE 

"In Messrs. Scott and Fraser's Specification on 'Reinforced Concrete' work, published 
in ion, sand is denned as 'all materials that will pass g-in. mesh and are retained on 
i -50th in. by 150th in. mesh,' this latter definition being adopted by the Concrete Institute in 
their Report on Testing. 

"'Shingle' is not a nice term to use for practical work, the two terms generally used 
being aggregate and coarse material. The term - shingle ' is very loose. 

" The author suggests that ' mud ' should be taken as all material which is less than that 
giving the critical diameter. The use of the term ' mud ' for concrete material opens the door 
to a very grave misuse in practical work. It has been stated in the past that a little clayey 
matter rather increases than otherwise the strength of concrete. This statement, however, must 
have been made upon imperfect data, as it entirely depends upon whether the clayey matter 
has any cementing properties, and most of the materials of this description found, at least 
in this country, have no cementing properties. 

" Clay, where it forms a coating on the aggregate or is a free agent, is most detrimental 
to the quality of concrete. With regard to the excess of water in concrete, this matter has 
been very thoroughly investigated, and in the Concrete Institute's Tests Report it will be 
found that the results are dealt with as to dry concrete, and further in a paper given by the 
writer before the Society of Architects last year. 

" Regarding the mixing of concrete, this is done at the present time in the most haphazard 
way, and the perfect mixing machine has yet to be arrived at." 

Extract from letter from Mr. Frank ] . Gray, Assoc.M.lnst.C .E. 

" The separation in a test-glass of water of a sample of newly-mixed concrete into 
measurable "layers of sand and cement and a measurable residue of ballast, is a test which 
can be used on works with confidence, and — what is most important — quickly enough to correct 
.my variation from specification as the mixing proceeds. 

" The conclusions which the author arrives at from his experiments are very helpful in 
understanding the weakening of free concrete placed under-water, and the detrimental effect 
of using an excess of water in mixing concrete. The differentiation between mud and sand by 
their rates of settlement referred to a datum line, is a good one. 

" I would like to ask the author whether he agrees that if particles of mud and sand be 
allowed to enter a tube of water at rates inversely proportional to their rates of settlement in 
water, such particles of sand and water would reach the bottom of the tube at the same time 
and form a mixture? " 

DISCUSSION. 

Professor Henry Adams, M.Inst. C.E., M.I.Mech E., M.S. A. (Vice-President Concrete 
Institute, etc.) : Speaking of the position of concrete in water, the author said that the water 
separated the materials. It seemed as if they separated entirely, but he imagined that the 
concrete would go down to a great extent as a single mass. When it is put into water in bulk 
it would retain, perhaps not its cohesion, but its position, much more than the author seems 
to imagine. 

He did not think water could percolate sufficiently to separate the mass into different sized 
particles, and deposit it in distinct layers. The depositing of concrete through water was at 
one time very constantly done by civil engineers in the construction of harbours and break- 
waters. 

The test given in the paper is a very simple and useful one to the engineer in charge of 
reinforced concrete work. In a very few minutes he can tell very closely what proportions are 
being actually adopted. It might also be applied to lime and sand in builders' mortar. That is 
always the difficulty, and many law ca-ses have been brought as to the quality of mortar in 
a building. This test might possibly apply to that. The indicator for machine mixing seems 
also to be very good. It seems absolutely necessary to get cheap mixing of the materials, and 
a few trials to indicate the number of turns would give great facility to the proper execution 
of the work. 

Mr. C. H. Colson, M.Inst C.E., M.C.I , in referring to Professor Adams's remarks as to 
concrete work under water, said that of course what the author had written did not apply to 
concrete work under water as it is generally understood by engineers, and he imagined that 
what was being referred to really was rather experimental work of putting concrete under water 
with the intention of separating it. As a general rule, when putting concrete under water, it 
pul down in a big --kip, and this -kip is put down on to the bottom before it is opened, and 
there is no actual fill of the concrete through water al ill. The doors are opened and the 
1 oni rete settles down at once in a big mass. 

For instance, he was at the present time putting down a good many thousand yards in 
three-yard skips. They go down on tli. bottom, and then open automatically, and the material 
268 



[A^n^EBiNG^d SETTLEMENT OF SOLIDS, ETC., ON CONCRETE. 

settles down as .1 big mass. There is washing of the top surface due to wave action, bul there 
is very little washing due to the water corning through the concrete. 

With regard to the discs falling in the water, it rather occurred to him thai ; they 

took up the position they did is simply a balance between force of gravity and the r 
oi the water to the falling of the things; that is to say, if you could ensure the disc, or what- 
ever it w.is, being kept in the upright position, it would drop at a very much greater speed, but 
slight irregularities on the bottom tend to start a delaying action. 

Mr. E. F lander Etchells, F.Phys.Soc, M.Math.A., AM.IMech.E. (Member of Council 

(J.I.) : The paper will be particularly useful in cases of dispute as to whethei 

or whether sand is clean, and also to settle that much debated question as to what thorough 
mixing is. 

It will also tend generally to obtain lietter mixing of concrete. The general practice now 
is to lay down concrete very gently, and to be very careful not to ram it so as to force all the 
lower contents to the top, and we recognise even balance mixing machines, but really sorting 
machines, where the concrete is sorted out of the different layers. 

With regard to the question of the size of sand, some mention has been made of the 
R.I.B.A. Report, but it should be recognised that the size of the mesh of a sieve is not neces- 
sarily intended to represent exactly the size of the largest grains. The question has been 
raided in more places than one as to fixing a smaller size as the upper limit for sand, but those 
who have had large experience of the actual work are well aware of the fact that, if sand 
is to flow readily through a sieve, it is no good having the sieve just the exact size of the 
largest sand this is to pass, but there must be plenty of margin for rapid and economical 
working. 

Regarding the author's statement " that the velocity of settlement varies directly as the 
square root of the specific gravity of the body minus the specific gravity of the liquid in which 
it settles," that is true, but it is ambiguous; and the ambiguity is not the fault of the author, 
but the fault of the English language, and it occurs wherever we try to put a mathematical 
expression into words. For example : 

V (S^L) = d = f 
\/(S-L) t s 

s is the specific gravity of the solid body ; / is the specific gravity of the liquid. This is 
the square root and the specific gravity of the body, minus that of the liquid in which it 
settles. (Illustrating.) This also is the square root of the specific gravity of the solid, minus 
that of the liquid in which it settles. The fault is we are short in the English language of 
something to indicate these values, and he did not know whether it might not be advisable for 
the author to put the expression in brackets behind the written words, since the written words 
used are not clear. 

He also would like to join the previous speaker in asking how the size of the particles was 
ascertained. r-20,oooth part of a square inch is very small, and it would be interesting to 
know by what means it was ascertainable. 

Mr. J. E. Hobbs: With regard to depositing concrete under water, he entirely agreed 
with the suggestions put forward by Mr. Colson, that especially when depositing in big 
lumps, that is two or three cubic yards, the bulk of the mass deposited at one time is not in 
any way influenced by the water, especially if the skip or the box lowering the concrete is 
carefully manipulated. 

V\ ith reference to the author's remarks as to excess of water in concrete, there is also the 
lack of water in concrete to be considered, especially nowadays wdien machine mixing is used. 
When mixing concrete, especially in a machine, it is just as detrimental to the concrete to be too 
dry as it is to be too wet. 

This leads up to the possibility of adopting a standard of saturation of concrete. Given a 
certain definite class of aggregate, it appears there should be a definite amount of water to 
be added when mixing a batch, whether when mixing by hand or in a machine, and he did not 
think any attempts had ever been made to standardise the amount of water put into the concrete, 
and suggested it might be worth while finding some point of saturation giving concrete of such 
a consistency that the tendency to disintegrate wdien being placed in a tank is to a large extent 
eliminated. With reference to concrete mixing, especially in machines, this is an entirely 
different proposition to mixing by hand. In mixing by hand, the practice has been in the past 
to turn over so many times dry and then so many times wet; but in machine mixing there are 
engineers at the present time who specify or try to enforce mixing in a machine, first dry and 
then wet. It is an absolute fallacy. 

<■'• 269 



THE CONCRETE INSTITUTE. [CONCRETE] 

Mr. H. J. Harding said he had had considerable experience in sand washing, having 
washed something like 1,000,000 tons. He noticed that what the author stated on this point 
was very accurate. 

As "to the question of the size of sand, mentioned in one of the letters, he made his 
definition of sand about a A-in. round hole washed through ; but it must be understood that 
washing sand through a sieve is a totally different thing from drifting it, and he had always 
found a i^th round hole is practically the same as a ^th square mesh, because a square mesh 
has a longer angle at the corners, so that sand washed through a gth square hole and sand 
washed through a -^th round hole is practically the same, but it would not be the same as sand 
sifted through in the ordinary course on a job. When Mfting sand, the moisture it contains 
must be taken into consideration. If it were very dry, it would sift very much more easily. 
The statement that sand should not be considered sand if it went through a 50 mesh was a great 
mistake. This also applied to concrete, because it means throwing away the most important 
part of the aggregate, and for this reason : if it is wanted to defeat percolation in cement that 
is finer sand, and finer sand to go down to a sieve of 100 mesh each way ; 100 meshes to the inch 
would be most useful to stop percolation with cement. He had tried this and knew it was 
correct, and therefore the Concrete Institute's definition ot sand as below 50 should be 
reconsidered. 

Professor Robert H. Smith, Assoc, M. Inst. C B., etc., said he rather demurred with Mr. 
Alban Scott to the author's use of the word " mud." It seems that on this subject it is very 
desirable, and perhaps necessary, to make careful distinction between those substances which 
contain any proportion of material that will actually go into solution in water and those that 
will not — that can only be held in water by suspension; and what is ordinarily called mud 
usually contains a considerable quantity of matter that may go into solution in water. The 
phrase "mud" may be very useful in this connection but it ought to be defined perhaps as 
material containing matter that will go into solution in water, and either "flour" or "dust" 
used for the stuff that Dr. Owens has called mud. 

Mr. M. Noel Ridley, Assoc. M. Inst. C.B. : With reference to the amount of water in 
concrete, he believed in a medium amount of water, but considered an excess of water, unless 
it is too great, is better than having really too dry a concrete, and that there should be no 
ramming, or next door to no ramming, of the concrete; ramming is a very bad thing. 

As to mixing the concrete twice dry, twice wet, in all his ordinary work he carried out 
this very specification, and with the happiest results, so that for ordinary work that specification 
need not be departed from. 

In depositing concrete in water, he did not think there should be so much fear of the 
separation of the particles in depositing under water. He had recently put down in 
12 ft. to 14 ft. of water a considerable amount of concrete. Xo skips were used, but shoots with 
open ends. The shoots were placed on the ground and then the concrete was put in, and when 
properly filled up the shoot was raised and moved about to the different parts, and the concrete 
was being shovelled into the shoot the whole time; and that made splendid concrete. Of 
course, that concrete was mixed a little bit stronger than in ordinary cases, but the results were 
absolutely satisfactory. 

Mr. Henry Pupiett, M Soc.E., M.C.I. : The author has dealt with a very important matter 
in treating of the mixing of concrete, because the most careful calculation, the most skilled 
design and the best workmanship may all be nullified by the use of improperly mixed concrete. 
With regard to mixing machines, it is almost impossible to get a properly machine-mixed 
concrete with any mixer in which the two operations of charging and discharging the machine 
can be carried out simultaneously. The only safety is the employment of a type of mixer 
which is rendered compulsorily intermittent by the application of some definite mechanical 
operation for the discharging of the concrete. 

Mr. T. A. Watson, M.C.I. : With regard to the idea that there is a certain definite 
proportion of water which should be added to the aggregate, this is not the case; there is a 
varying definite proportion, but it is not a definite proportion, and there is a certain amount 
of latitude which must be allowed, or should be allowed, to contractors by engineers in that 
proportion, because the dr\ mess of the aggregate controls it in one way, the weather controls it 
in another; and altogether there are several outside sources, and no definite hard-and-fast rule 
is wanted that there is a certain amount of water that has to be put with concrete that is 
comi>osed of certain proportions of ballast, sand and cement. 

Mr. H. J. Sbelbourne : With regard to fixing the quantity of water in the quantity of 
concrete or the quantity of aggregate, engineers who oonsidei the question should have regard 
to the fact that practically no two aggregates in no two places would have an accurate 



[&gNGnSr%IS SETTLEMENT OF SOLIDS, ETC., ON CONCRETE. 

measurement, and the quantity of water necessary to mix a certain quantity of concrete with a 
certain amount of aggregate would depend very largely upon the amount of the individual 
atoms composing the aggregate itself. 

DR. OWENS'S REPLY. 

With reference to the thickness of the cement layer, he had not had time to describe 
in detail the steps by which he arrived at that, but he found that when the cement settles 
through the water at a certain depth down below the surface it acquires what is called a 
surface of separation — it defines a surface quite clearly. Then, that goes on settling for another 
period, until a time is reached — about 10 minutes — when it ceases to contract, and it duo nol gel 
any thinner than that ; and there appears to be a certain amount of water which it will not 
lose — that is between the interstices — and that is the time to measure, and it is easy to tell by 
watching it when it ceases to contract. 

A good deal of discussion has centred around the definition of sand and shingle. Tin- 
question is, perhaps, somewhat misunderstood : Is there a difference between sand and 
shingle, or are we asked to give an arbitrary definition between two things? There is a 
natural line drawn by nature between particles above a certain size and below, and we ought 
to consider the things below that as sand, above as shingle. 

The elimination of all particles below what passes through a 50 mesh had also been referred 
to, and he was very strongly of the opinion that that is a mistake. There is no reason whatever 
for eliminating those particles. As a matter of fact, the very finest particles, even down to 
i-i,oooth of an in. will act just as well as the coarser particles, and somewhat better, from some 
points of view, in making concrete. 

One very important point referred to is the question of the porosity of concrete. It is a 
well-known fact that particles of uniform size, when placed in a vessel, contain the maximum 
amount of air space or voids. If it is wished to reduce the amount of void, it can be done by 
introducing smaller particles which will fit between the larger ones, and this can be done to 
infinity until it is solid. The removal of those little particles which pass the 50 by 50 mesh 
is leaving vacancies which must be filled by cement or left empty. If they are left empty, 
porous concrete is the result. 

There has been some misunderstanding with reference to the deposit of concrete under 
water. Professor Adams, Mr. Colson, and several other gentlemen have referred to it. 
What it was intended to convey was that small pieces of concrete must not be dropped 
and allowed to settle through any depth of water, such as throwing concrete into a trench with 
a shovel. Of course, it is perfectly sound practice to put concrete through water in a big 
skip which can be opened when it has reached the bottom or through a shoot if the water 
is sufficiently shallow; there is another method adopted in trench work: that is to put the 
concrete in above the surface, then put fresh concrete on the part above the surface, and it will 
push the other along so that it will not fall through the water. 

As to Mr. Etchell's remarks on the gauging of sand by a sieve. There is rather a curious 
point; it is surely perfectly well-known. The particles of sand which fall through a sieve very 
often fall end-wise, that is measuring the minimum diameter ; in fact, if the particles which 
have passed through a sieve are put on the stage of a microscope and their diameter measure:* 
it will be found that it is maximum diameter which is being taken. 

Mr. Ridley referred to the lack of water being as bad as having too much. As the 
Chairman has very wisely said, there must be neither too much, nor too little; there is a 
proper mean. If there is too little the concrete gets sticky, and you cannot mix it; while if 
more is used porous concrete results. 

It ought also to be made quite clear that it is utterly impossible to fix the amount of water 
to be added to concrete, because there are several things which govern this point. The amount 
of water which concrete should contain can be fixed, but that is quite a different thing. The 
amount which is to be added depends upon the amount which is already present in tht 
aggregate and also in the porosity of the aggregate, also upon the shape of the particles, and 
upon various other things, but it is impossible to tell what that should be except by judging 
from the appearance of the concrete after it is made. 

Professor Smith referred to the difference between mud and sand. Of course, the word 
mud requires to be accurately defined to base any statement upon differences between mud and 
clay or mud and sand, but in the ordinary meaning of the word it does not seem necessary 
that one should consider that mud is something which is matter, which can go into solution. 
The author concluded by answering some other remarks of Professor Smith and on the evils 
of over mixing, and the meeting then concluded. 

E2 2 7« 



THE CONCRETE INSTITUTE. [CONCRETE 



STEEL FRAME BUILDINGS IN LONDON. 

By S. BYLANDER, Chairman, Junior Institution of Engineers, M C.I. 

The following is a short risume of Mr. Bylander's Paper rend before the Institute on 
February 13th, 1913, as tar as it deals with his views as to steel-frame buildings 
generally. As the three buildings particularly described in this Paper — viz. : The Ritz 
Hotel, Selfridge's Stores, and the Royal Automobile Club—have been fully described 
Gnu illustrated in former issues of our journal* that portion of Mr. Bylander's Paper 
is not reported here. 

In opening, the author remarked that he believed this was the first paper an the 
subject of steelwork construction which has been presented, and he was glad to 
see that the Concrete Institute had decided to invite papers and discussions on subjects 
within a broader range — namely, upon structural engineering generally — instead of 
confining them to the particular aspects of concrete and reinforced concrete only. 

In this paper it is not proposed to give a comparison of advantages and disadvan- 
tages of steel buildings and reinforced concrete buildings, but to put forward a few 
factors which are of importance to the designer. The reinforced concrete engineer and 
the structural steel engineer have many interests in common, and their co-operation 
"s an advantage. The advancement oi knowledge of the use of different materials 
is essentially necessary before any progress can be made. 

The question of whether reinforced concrete, steel, or other material shad be vised 
in a particular building must be left to the decision of the architect, engineer, or 
estimator, who has made a careful study of the requirements in each case. 

There is not vet any golden, general rule to determine when and where a particular 
material is most suitable. The only rule which is possible of application is use each 
material to its greatest advantage. 

Good engineering judgment, based on practical experience, combined with careful 
eiesign and accurate calculation, is required to obtain the best results. 

STEEL FRAME BUILDINGS IN LONDON BEFORE THE YEAR 1909. 

The use of steelwork for the skeleton of the building before the passing of the 
L.C.C. General Powers Act of 1909 was relatively small. Considerable progress has 
taken place during the last ten years, and it i& very interesting to compare the con- 
struction used ten years ago and that which is now gradually being introduced. 

He believed the Ritz Hotel was the first building in London to be designed on 
the cage construction principle, about the year 1904. The usual construction at that 
time was to emplov some steelwork in the internal part of the building only, or to 
carrv the external wall at the first floor level on steelwork to permit large shop 
windows, and sometimes steel pillars were used to strengthen external walls. Where 
fire-resisting buildings were required, the floors were usually constructed with solid 
plain concrete, carried on steel beams 2 ft. to 3 ft. centres, but very little precaution 
was taken for stability or protection against fire for the individual steel members. The 
pillars were generally made in one-story lengths, with caps and bases. 

At that time there were no recognised standard sections, but each mill rolled their 
own particular shapes. These conditions made it very difficult for the structural 
engineer to select the most economical sections, and a very great improvement has 
taken place through the standardisation of sections. 

L.C.C. 1909 ACT. 
The passing of the L.C.C. General Powers Act in 19,0a had a verv good effect upon 

the method of construction. It is to be regretted that the Act does not applv to 
buildings designed according to the old Act ; nevertheless, the introduction of recog- 
nised standard stresses and a general method of design and supervision will tend to 
simplification and economy in design and fairer competition and safer structures. 

No Act can be satisfactory to all, but it would have been better if the building code had 
taken the form of regulations by the London County Council instead of an Act of 
Parliament. All regulations in connection with engineering must necessarily be 
revised periodically as the science and practice advances, and it is to be hoped that 
at a not too far distant future this Institute will urge the London County Council 10 
obtain powers to issue new regulations in a more complete form. 

» Vol. I.. No. 6. Vol. IV., No. 1. Vol. VI., No. 3. 
272 



(&a u S A H STEEL FRAME BUILDINGS IN LONDON. 



ECCENTRIC LOADING. 

Stresses from eccentric loads are always produced on pillars either on account of 
imperfect bearing under the base, in the joints, or on the cap; these may be i I 
accidental eccentric loads. Loads carried on brackets, or otherwise placed eccentrically 

to the axis of the pillar, may he called intentional eccentric loads. The loads p 
on the cap of the column should in mosl cases he calculated a-- eccentric loads, although 
at first sight it may appear that the load is placed concentric. On account of the 
deflection of the beams a bending moment is produced on the pillar, and allowance 
should be made for this when fixing a safe stress for the pillar. 

Another factor affecting the safe stress which is of very great importance is the 
question of the iusct or edge distance of the section. 

More consideration should be given to the question of reduction of strength of the 
pillar section by rivet-holes. A safe stress for a direct load for a pillar should be set 
90 low that an increase of 10 per cent, due to intentional eccentric loading will be 
permitted, and where the eccentric load is greater, the sections should be increased 
correspondingly to 90 per cent, of the eccentric load only. By this means detail 
calculations for very small eccentric loading will not be required, and the engineer who 
calculates everything carefully and in detail will not be placed at a disadvantage as 
compared with those who do not go into details so completely. The maximum direct 
stress should be set so low that a slight bending should not necessitate increase . ! 
section. On the other hand, he thoroughly believed that pillars should be calculated for 
eccentric intentional loads. 

ACCURACY OF CALCULATIONS AND DRAWINGS. 

The chief point in connection with satisfactory and economical design is accuracy 
of drawings and calculations. Higher stresses can be used when all loads and stresses 
are accurately calculated, and when drawings are made so complete that no alterations, 
or very slight alterations, are necessary in the final work, and when the work is well 
supervised. 

The economic use of materials necessitates stressing same as high as is consistent 
with safety, and in order to use high stresses great care and accuracy must be exercised. 
These rules apply equal!)' well to steelwork and reinforced concrete. The plans for a 
structure should be laid out with due consideration to the employment of the materials 
intended. Spacing of pillars, depth and span of girders, spacing of beams, etc., affect 
the cost to a very considerable extent. It is hardly realised how much extra it costs to 
make the beams very shallow; very often double the material is put in beams because 
the original plans have been made with the assumption that shallow beams should be 
used in order to obtain greater head room. It can be said generallv for steelwork as 
well as reinforced concrete work the depth of beams of about i-i2th to i-i5th of the 
span is economical, and the spacing of pillars from 15 ft. to 20 ft. is also satisfactorv. 
It is still more economical to place the pillars closer in one direction than the other in 
ctder to use only primary beams and no secondary beams. This, however, is seldom 
possible in ordinary buildings in London. 

SURVEY OF SITE. 

The first thing to start with in preparing a set of working drawings for a build- 
ing shou'.d be to have an accurate survey of the site, from which to prepare dimensioned 
plans for walls and pillars. Unless accurate dimensions are obtained at an earlv date, 
the plans cannot be made correct to scale, which obviously will affect the accuracy of 
the calculations for loads and bending moments. 

SIMPLIFIED CALCULATIONS. 

The author has adopted the practice of using one sheet of paper, quarto size, for 
the calculation of each piece. Each piece has a mark or identification number, and 
this is used as the sheet number on the calculation sheet. This method will facilitate 
keeping of records, and avoid mistakes in connection with the alterations. It also 
permits of using printed sheets, and thus reduces the labour of repeating sketches and 
writing. He further believed that the adoption of pounds as a unit of weights instead 
of hundredweights or tons is an advantage, for the reason that in close calculations 
one must deal with smaller unit weights than hundredweights, and decimals of 
hundredweights and tons are not desirable. If pounds are used, the wen I 

173 



THE CONCRETE INSTITUTE. [COlNCBEXEj 

materials or the assumed superload can easily be varied a relatively small amount to 
suit requirements. The calculations of the dead weight of floors can be conveniently 
made as follows : Assume reinforced concrete weighs one pound per square inch of 
section of beam or slab per foot run, thus, the slab 6 in. thick and 12 in. wide would 
weigh 72 lb. per foot run, and an 8 in. by 4 in. concrete beam 32 lb. One pound per 
square inch per foot run is equivalent to 144 lb. per cu. ft. — which is for all practical 
purposes a fair average weight. The result is that the weight calculated can be used 
directly as load to be ""carried without transferring same into hundredweights or tons. 
Pounds are very suitable for unit weights and loads, but the pound is too small a unit 
for big loads. He had, therefore, adopted 1,000 lb. as a unit for big loads, and he 
called 1,000 lb. one kip, derived from kilo ( = thousand) and p ( = pounds). To transfer 
from one unit to the other only necessitates moving the decimal point three places. 
A great amount of labour has been saved and mistakes have been avoided. The bending 
moment may be expressed in kips and inches, and the unit length of one inch is there- 
fore used in the calculations throughout. 

The stresses are generally given in pounds per square inch, except in the case of 
b)g areas, such as brickwork and ordinary concrete foundations, etc., where the 
pressure is given in kips per square foot. 

DRAWINGS. 
The drawings required for the steel structure may be divided into three classes : 
(1) plans, (2) constructional details, (3) shop details. 

Plans. — The plans should show the general design, position of pillars and beams, 
and give all main sections and mark of every separate piece that is sent to the site. 

Constructional Details. — Constructional details are required to illustrate and make 
clear the connect ions, riveting, machining, and all general requirements, the relative 
•dimensions between steelwork and stonework, etc. 

Shop Details. — These are made for use in the shop, and should show every dimen- 
sion required to make the piece complete, and should not be merely constructional 
details leaving the accurate positions of rivets to be determined by the workmen in the 
shop. 

It is of equal importance to have clear constructional details and shop drawings as 
to have carefullv designed general plans. Unless the shop details are carefully worked 
out for dimensions given on the drawings, showing rivet spacing, sizes of rivets, edge 
distances, accurate position of open holes for field rivets, notes of special requirements 
such as cutting, machining, countersinking, etc., it is not possible to obtain satisfactory 
work on the site. 

All details should be completed in the office by the draughtsman and properly 
checked before the orders are issued to the shop. The checking cannot be done so 
eftectively in the shop as is possible in the office, and the cost of making alterations of 
the steelwork on the site is much greater than the cost of checking and correcting the 
details in the office. 

PROGRESS OF WORK. 
Systematic working throughout will prevent mistakes and difficulties, and procure 
satisfactory work and speedy erection. 

Order Lists.— When the shop drawings are finished mill order lists are prepared, 
giving section and size of material required, and the material is ordered from the 
rowing-mills. Then shop order lists are prepared for all duplicate work such as cleats, 
brackets, and stiffeners, and these order lists, together with the shop details, are sent 
to the shop and the work is put in hand. 

During the progress of rolling and manufacture an inspector supervises the work, 
tests the material, checks all dimensions from the detail drawing, inspects the finished 
member, and approves or rejects same before it is sent to the site for erection. The 
inspector sends weekly reports to the engineer giving the marks of the pieces, stating : 
(1) material rolled, (2) pieces assembled, (3) pieces finished, and (4) pieces sent to site. 
Iii this manner the engineer can supervise the satisfactory progress of the work, and 
take precautions to avoid delay. The erection is a very simple matter if the pillar'- are 
eel in accurate positions .according to the pillar plain and the walls built to the 
dimensioned plans and details. The erection can proceed with great speed, as all pieces 
are made to exacl dimension, and must fit when delivered, care being taken in making 
the design to allow for easy erection and the minimum amount of field riveting. 

274 



y ! C-CN^IUUCTIONAn 



REINFORCED CONCRETE EXTENSIONS 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reliable information -will be presented of ne-w -works in course o; 
construction or completed, and the examples selected -will be from all parts of the world. 
It is not the intention to describe these -works in detail, but rather to indicate their existence 
and illustrate their primary features, at the most explaining the idea -which served as a basis 
for the design. — ED. 

REINFORCED CONCRETE EXTENSIONS TO ELECTRICITY WORKS 
HULL CORPORATION. 

The works described below include new engine-house and boiler-house with overhead 
coal bunker, now in course of erection at the Sculcoates Lane Electricity Works of 
the Hull Corporation. 

The engine-house, which is being erected at the end of the existing engine-house, 
has a width of 65 ft. between walls, a height of 26 ft. 6 in. to eaves, and a length of 

107 ft., with provision for future extension. 

The turbo and condenser foundations are 
built of mass concrete upon a cluster of pitch 
pine piles, with basements running each side 
at a level 12 ft. 6 in. below main floors. The 
floors, which have been calculated to take a 
dead load of 3 cwt. per sup. ft., consist of 
b-in. reinforced concrete slabs resting on cross- 
beams 15 in. by 20 in., forming girders of 
the usual T-section, and are reinforced by 
5-in. round rods with |-in. stirrups to take 
up excess of shear. The sides and gable are 
composed of curtain walls 6 in. thick below 
and 5 in. thick above floor level, reinforced 
by |-in. rods vertically and horizontally at 
6-in. centres below and 18-in. centres above 
floor level, with footings 5 ft. by 1 ft. 9 in. 
with f-in. rod reinforcements. 

The walls are stiffened by pilasters 24 in. 
by 12 in., each pilaster containing a 12-in. 
by 6-in. R.S.J., which joists at the side re- 
ceive the shoes of roof trusses ; while at each 
alternate pilaster there are piers 14 in. bv 

24 in., with f-in. vertical reinforcement and 
5-in. wire lacing, carried to a height of iq ft. 
4 in. to receive longitudinal girders for travel- 
ling crane. 

The boiler-house, which has a span of 
100 ft. and is 90 ft. long, with provision, as 
in the case of the engine-house, for future 
extension, is made up of a central basement 

25 ft. wide by 10 ft. 6 in. high, with boiler 
foundations on each side and main boiler- 
house floor above, with overhead coal bunker 
34 ft. from floor level. 

The roof is composed of steel lattice 
girders secured at the outer walls to the 
R.S.J.s previously mentioned, and on the 
inner side by Lewis bolts to the sides of tlie 
coal bunker. 

The floors are made up of reinforced con- 
crete slabs 7 in. thick on the main floor and 
b in. thick in the basement, resting upon 
crossbeams iS in. bv 24 in., and tin 

275 




Plan of Coal Bunker. 
Ki.ectricity Works Extension, Hill Corpor 



NEW WORKS IN CONCRETE. 



[C ONCRETE! 



beams are reinforced in a similar manner to the engine-house, with additional longi- 
tudinal beams in the top floor to carry railway, which will be used temporarily pending 
the complete installation of mechanical stoking. 




The boiler foundations and flue arc made up of <)-in. concrete slabs similarly 
reinforced, lined with o-in. fireclay brickwork, and carried upon crossbeams 

276 



E 



CONSTBUCTIONA D 
KMCiTNEERlNG — J 



REINFORCED CONCRETE EXTENSIONS. 




View of Reinfoirced Concrete Columns supporting Reinforced Concrete Coal Bunker. 




Interior of Turbo Room. 
Electricity Extension Works, Hill Corporation. 



■ 



NEW WORKS IN CONCRETE. 



[CONCRET E) 



18 in. by 20 in., and 18 in. by 34 in. respectively, fronl which, in the case of the flue, 
they are separated by a sand joint to allow of tree expansion and contraction. 

The overhead coal hunker, as will be seen from the accompanying section, extends 
the whole length of the boiler-house, and is carried upon six reinforced concrete 
stanchions each 5 ft. by 3 ft. by 44 ft. long, supported upon a reinforced concrete 




Details of Bunker Foundations and Stanchions. 
Electricity Extension Works, Hill Corporation. 

fooling, of which detail is given below, 13 ft. 6 in. by ft. 6 in. by 4 ft. 6 in., rein- 
forced by a grillage of 2-in. bulb tees with {-in. stirrups to take up excess of shear. 

These footings are carried in turn upon clusters of pitch pine piles 14 in. by 14 in. 
The stanchions are built of 2 — 1 — 1 shingle concrete reinforced by 28 No. i^-in. 
round rods with {in. lacing at 2$-in. centres, and base been d< -igned to take a 
maximum load of 1,012 tons. 
278 



g 



OONSTPIXTIONAI,! 



^ 



REINFORCED CONCRETE EXTENSIONS. 




79 



NEW WORKS IN CONCRETE. [CONCRETE] 

The coal bunker is 35 ft. wide, 33 fl. high, and 95 ft. long, the underside being 
battered up at 40 dig. at gable to conveyor level, with a wood partition at the other 
(temporary) end. 

The arrangement and the number of Lhe supports of the coal bunker wen- 
governed by the positions of the water tube boilers and the necessity of providing an 
uninterrupted space between the fronts of the two rows of boilers. As only six points 
of support were available, the stanchions had to be of considerable sectional area. 
The capacity of the coal bunker is 2,000 tons. 

It is formed of 7-in. reinforced concrete sides, with top and bottom booms 48 in. 
by 30 in. carrying over a span of 40 ft., and a central longitudinal beam 9 ft. by 
1 ft. 6 in. resting upon cross-beams over stanchions and intermediately. 

The slabs are reinforced by i-in. round rods at 4-in. centres, double reinforcement, 
horizontally and vertically, with \-in. rods diagonally over supports to take up excess 
of shear, while the booms and cross-beams are reinforced by i^-in. round rods. The 
bottom of the bunker is formed into pyramidal 6-in. slab hoppers carried upon canti- 
levers 12 in. wide with a maximum depth of 7 ft. 6 in. from sides and cross-beams, 
which batter to 18-in. outlets 34 ft. from floor level. 

The slabs are reinforced by ^-in. round rods, while the cantilevers are reinforced 
by ij-in. rods at top, and f-in. rods at bottom, with f-in. diameter lacing for shear. 

The top of the bunker is formed by a steel truss roof carrying conveyor chamber 
12 ft. 6 in. wide by 10 ft. 6 in. high, with steel floor, and sides formed' of " Hv-rib," 
in which a bucket conveyor works, lifting coal into the hoppers from an underground 
coal bunker. 

This chamber is covered with steel trussed, slated roof, with ridge 100 ft. from 
boiler-house floor. 

Additional works comprise large underground pump chamber and drainage sump, 
an underground ashpit and coal bunker, and two exhaust sumps, all in reinforced 
concrete, with cloakroom and the usual offices. 

There is also a switchboard chamber, 65 ft. long by i-| ft. wide bv 26 ft. 6 in. high, 
along the south side of engine-house, built in reinforced concrete, but faced in brick- 
work to correspond with the adjoining (existing) buildings. 

The foundations being soft clay upon a bed of peat, capable of bearing a load of 
only about 14 cwt. per sup. ft., it was found necessary to pile the whole site, 400 pitch 
pine piles being used for the purpose. 

Owing to the nature of the foundations, large beams with low percentage of rein- 
forcement have been favoured, as giving additional lateral rigiditv. 

The buildings have been specially considered in design with the view- of making 
them as fire-resisting as possible. Except the light wood lathing for securing the 
slates, the whole of the roofs are of steel, and, as an additional protection, large 
asbestos slabs about ys in- thick are to be screwed to the lathing. 

The whole of the work was erected to the design of Mr. A. E. White, M.Inst.C.E., 
City Engineer, Hull, the contractor for the reinforced concrete and builders' work 
being Mr. J. T. Levitt, Hull, and Messrs. E. C. and J. Keay, Ltd., Birmingham, for 
tlie constructional steelwork. 

REINFORCED CONCRETE BRIDGE IN FRANCE. 

The bridge here illustrated has recently been erected at Seytenex, near Annecy, in 
Savoy, France, by Messrs. Mazet and Limousin, Contractors and Licensees of the 
Coignet System at Lyons. 

As shown in the illustration (frontispiece), this bridge spans a deep valley, at the 
bottom of which runs a river, and the foundations of the abutments and the piers are 
constructed on the rock. 

This particular type of bridge is similar to the one which was erected about 
fifteen years ago, also on the Coignet System, at Luxemburg. It may be described as 
a composite structure, the arc lies, piers, and abutments being in stone masonry, and 
the superstructure being entirely in reinforced concrete. 

A noticeable feature of this particular type of bridge is that it is composed of two 
parallel arches in stone masonry, instead of the usual single masonry arch, which is, 
of course, more costly and more complicated to erect. In this case tin 1 scaffolding for 
one of the masonry arches is shifted, after the work has been completed, and used 
for the construction of the adjoining arch, so that much lighter scaffolding is required 
than by the usual method, lie two arches are connected together by the reinforced 
280 






I 



,C0N$TWUCT]ONAi: 
ENOIMEEKINO- — 1 



REINFORCED CONCRETE BRIDCE. 




truc- 
ture, v hii h they 
support, 
of the pi : 
arches of this bridge 
in i a su r< 
mately [40 ft., and 
the two smaller 
arches at eai h end 
have a span of about 
43 ft. The deck and 
the arches are calcu- 
l.ii' d for ordinary 
road traffic, the heavi- 
est moving load being 
that of a steam-roller 
weighing 15 tons. 
The principal mas- 
onry arches measure 
approximately 5 ft. 
at the springing and 
3 ft. in the middle. 

A.^ stone is easily 
procurable in this 
particular district, it 
was found m o r e 
'economical to maki 
the arches in this 
manner than in con- 
crete or reinforced 
concrete. 

As shown in the 
accompanying eleva- 
tion and plan, the 
weight of the road- 
way and deck is 
transmitted on to 
the twin masonry 
arches bv means of 
a series of pillars. 
The footpaths on 
cither side support- 
ing an iron railing 
are cantilevt red and 
supported at inter- 
vals by means of 
brackets. The width 
of the roadway is 
approximately 13 ft., 
and the total width 
of the bridge, includ- 
ing both side walks, 
is approximately 18 
ft. The in- 
arches have a width 
of about 4 ft., and 
the interval b< 
them is about 7 ft. 

T h e rein! 
concrete 

ture, which includes 
281 



NEW WORKS IN CONCRETE. 



[CONCRETE 




282 



I 



CONSTKl ICTIONaT] 
ENGINEERING — J 



REINFORCED CONCRETE IN SOUTH WALES. 



the pillars, tie beams, and the dirk, is executed on the Coignet Sj I hi 

composed ol a special arrangemenl of round bars of mild steel. The pillars contain 
four bars at each corner, held together by means of spiral ties of small diameter, 
longitudinal beams contain two main bars in the bottom portion working in i 

and two upper 
bars in the top 
portion of the 
beam working 
in compression, 
the two set-, of 
b a r s be i n g 
united by means 
of small-diame- 
ter round bars i >r 
stirrups, which 
are intended to 
resist the 
shearing efforts 
in the beams. 
The transverse 
beams under- 
neath the floor 
slab, uniting the 
two parallel 
rows of pillars 
above the 
arches, and sup- 
porting also the 
decking, contain 
three bars in 
tension and 
three bars 
in compression, 
also united by 
means of stir- 
rups. The deck- 
ing itself, which 
is about 5 in. in 
thickness, con- 
tains a mesh- 
work of round 
bars. The rein- 
forced concrete 
decking is cov- 
ered by means 
of a certain 
thickness of 
richer concrete 
laid to fall to 
prevent the per- 
colation of water 
thro u g h t h e 
reinforced con- 
crete deck, and 
the roadway is 
made up by means of about 9 in. of ordinary road metalling. 




TINPLATE WORKS. LLANELLY. SOUTH WALES. 



The accompanying illustrations 
concrete blocks. 



ow some works recently erected with " N\ ins 



281 



NEW WORKS IN CONCRETE. 



[CONCEEm 



The main building contains a travelling overhead oran€ carried on steel columns; 
The wall panels between the steel columns are 18 ft. 8 in. wick' by 35 ft. high, and ate 
filled in with 32 in. by () in. by 9 in. hollow concrete blocks. 25,299 blocks were 
n cjiiired in construction. 

The workshops, pickling-house, engine-house, and tin-house were all erected with 
hollow eonerete. block- as above, the number used being 18,219. 

The photograph below shows that concrete block-, are admirably adapted for 
industrial purposes, and it will be noted that the walls an- built " honeycomb " fashion 
for ventilation and the escape of fume- arising in the course of manufacturing tinplates. 




Tinplate Works, Llaxelly, South Wales. 

The boundary wall (p. 283) was a'.so constructed with " YVinget " blocks, its length 
being 587 ft. and the height 10 ft. ; 5,602 blocks were required for its erection, and to 
finish same 220 lengths of coping 32 in. by 12 in. by 9 in. were required, the latter also 
being made on the " YVinget " machine. 

Thus the total number of concrete blocks used on this contract was 49,110. The 
blocks were made on a " Winget " concrete block-making machine, and the concrete 
was mixed in one of the company's " Express " mixers. The output of blocks averaged 
400 per working day. The contractor was Mr. S. E. Clay, Nuneaton, for Messrs. R. 
Thomas & Co.," Ltd., of Llanelly, South Wales, and the architect was Mr. W. H. 
Walker, 12, Cherry Street, Birmingham. 



284 



[j, CONSTRUCTIONAL] 
' >■ ENGINEERING — J 



NEW BOOKS. 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary 01 some of the leading books -which have appeared during the last few months. 



" Structural Details of Hip and Valley 
Rafters." By Carlton Thomas Bishop. 

London: Chapman & Hall, Ltd., 11 Henrietta Street, 
Covent Garden, VV.C. 72 + vpp. Price 7/6 net. 

Contents. — General Outline — Flange Con- 
nectian — Web Connection — Notes on 
Other Cases — Derivation of Formulas 
- — Graphic Method of Determining 
Angles — Values and Logarithms for 
Common Cases. 

This volume is illustrated with numer- 
ous drawings which show the method of 
working for the various cases which are 
described, and a great deal of care has 
been exercised by the author in the pre- 
paration of these diagrams, which are 
clear and well drawn. 

There is no doubt that the detailing of 
hip and valley rafters with the various 
connections is a matter that is likely to 
cause a great amount of trouble to the 
inexperienced draughtsman, and a volume 
devoted entirely to this section of con- 
structional work should be of value. It 
is rather surprising to find that so much 
matter can be presented by such a limited 
subject, but there certainly do not ap- 
pear to be any superfluous notes or draw- 
ings. The method of finding the neces- 
sary numerical values, both algebraically 
and graphically, is fully explained, and 
much of the calculation is simplified by 
means of tables. The book is well pre- 
pared, and although its use will obviously 
be limited, as the subject is not one which 
has to be dealt with every day, there is 
no doubt that it will meet the needs of the 
structural draughtsman when he is en- 
gaged in solving problems in hip and 
valley construction. 

" Fire Tests with Roof Coverings of Asbestos 
Cement Corrugated Sheets Submitted 
for Test by the Asbestos Manufactures 
Co. Ltd." 

Red Book No. 174 of the British Fire Prevention Com- 
mittee. Published at the Offices of the Committee, 
8 Waterloo Place, S W. Price 2/6.* 

This Red book deals with tests under- 
taken with eight roofs covered with 
asbestos cement corrugated roofing, with 
pitches of 32 , 45 , and 68°. 

In the case of roofs 1 to 4 the roofing 
was on boarding, for roofs 5 and 6 the 
roofing rested on purlins, and in roofs 7 



and 8 tin- ends <>f the roofing were bedded 
on the wall. 

The tests were of 30 minutes', 45 
minutes' and 60 minutes' duration. 

In sonic cases the removal of the fire 
was to be followed by the application of 
water, whereas in others no water was 
to be played upon the roof. 

The progress of the various tests is 
given in the form of logs, and in each 
case the observations after test recorded. 
The report is excellently illustrated, and 
all dimensions are given, with metric 
equivalents. 

*(A German edition of the Report has also been 
issued by the Committee's Continental Publishers 
(The Rechtsverlag, 6a Konigstrasse, Hannover). 

"Experiments with Fixed Beams" (" Ver- 
suche mlt eingespannten BalKen"). By 
Dr. F. E. von Emperger. 

Leipzig and Vienna : Franz Deutike. 1913. Price Mk 10. 

The reinforced concrete committee of the 
Austrian Association of Engineers and 
Architects planned a series of experiments 
on the strength of beams fixed at both 
ends, which have been carried out by Dr. 
von Emperger, and are now described in 
his report. Some freely supported beams 
wore included for purposes of comparison, 
as well as some balance d by a load beyond 
the bearing. The beams were prepared and 
tested at the Association's testing place at 
Heiligenstadt. The testing method em- 
ployed was the simple one devised by Dr. 
von Emperger, and previously described in 
this journal. Delicate instruments of the 
Martens type were used for the measure- 
ment of deflections. In addition, as 
is usual in Continental work, each beam 
was photographed at the stage at which 
cracks became visible, and a complete re- 
cord of the manner of fracture was ob- 
tained. The effect of the loading on the 
walls into which the beams were built 
was also observed and recorded. 

The principal conclusions arrived at as 
the result of these very extensive test*, 
are : — 

1. Every beam which is not specially 
constructed as a freely supported beam 
should be regarded as at least partial 1 ■ 
fixed, and the reinforcement at the ends 
should be distributed accordingly. 



2*5 



NEW BOOKS. 



[CONCRETE 



compression zone should never be entirely 
free from reinforcement. 

2. In computation, the moment of 
flexure at the bearings must always be 
taken into account as well as the bending 
moment in the middle. 

}. Where proper connection is made be- 
tween the beam and its bearings, the 
beam may be regarded as completely fixed*, 

and a moment of 9- = o*o8j ql- may be 

12 
assumed at the ends and one-half of that 
value in the middle. The bearing is to 
be regarded as including not only a sec- 
tion of the wall of the same breadth as 
the beam, but a wider section depending 
on the quality of the material in the wall. 

4. In doubtful cases a less degree of 
fixing may be assumed. The experiments 
show that the distribution of stress adapts 
itself to the reinforcement. 

5. The most complete fixing is obtained 
bv completely connecting the reinforcement 
of the beam with the bearing, as in frame 
construction. In the absence of such a 
plan, the ends of the reinforcing rods may 
be merely bent over and embedded in the 
concrete of the bearing wall. 

6. With sufficiently rigid connection, the 
beam and bearing wall may be computed 
as a statical whole. 

7. Where the wall is of brickwork set 
in lime mortar, it is advisable to compute 
the beam as if freely supported, but to 
provide for partial fixing by bending up 
the reinforcing rods. A suitable support 
of Portland cement concrete may, how- 
ever, be built into the wall. 

8. The construction of corbels at the 



ends of the beams is of advantage. \\ hen 
these are large, the construction behaves 
as a cantilever, and the stresses are 
greatly diminished. 

"Concrete Building Blocks" I ' Der Beton- 
BaublocK". By Max Keller. 

Berlin: \'erlag derTonindustrie Zeitung.1913. Price Mk 3. 

This little work deals, clearly and com- 
pactly, with the use of concrete blocks in 
building. The types of hollow block de- 
scribed are classified as American, Rus- 
sian, Austrian, and German, and examples 
of the application of most of these are 
given. The variety of the constructions 
described is considerable, ranging from 
boundary walls and farm buildings to a 
large water-tower, which also serves the 
purpose of a view-tower. Concrete blocks 
have also found considerable application 
in Germany in the erection of buildings 
for military purposes on manoeuvring 
grounds, in place of the usual corrugated 
iron structures. A detailed account of the 
methods of manufacture is given, and 
one chapter contains the plans and draw- 
ings for a detached house of satisfactory 
architectural appearance constructed with 
" Phoenix " hollow blocks. The lintels, 
sills, etc., are in artificial stone, and the 
roof of cement tiles. The cost of hollow 
blocks is computed to vary from 10 to 17 
marks per cubic metre, an average value 
being 14 marks. This is assuming that 
only a single machine is used, requiring 
the services of two men. Details of tests 
are also given, and the book contains 
much useful information concerning this 
very useful and simple method of con- 
struction. 



EDITORIAL MEMOS. 

CONTRIBUTIONS— Original contributions and 
illustrations are specially invited from engineers, 
architects, surveyors, chemists, and others engaged 
in practical or research work. NISS. should be written 
on one side of the paper only, givins? full name and 
address of the author. 

The copyright of any matter accepted for pub- 
lication is vested solely in the proprietors of the 
journal to be used in any form they think fit, unless 
there be a special arrangement. 

MSS. and drawings or photographs are sent in at 
the author's risk. Every effort will, however, be 
made to return unsuitable communications. 



PUBLISHER'S NOTICES. 

DATES OF ISSUE.— This Journal is issued 
Monthly. For Advertisement Rates apply to Pub- 
lisher. Matter for displayed advertisements required 
by 12th of month prior to subsequent issue, for 
Wants column by 18th. 



SUBSCRIPTION RATES (Prepaid. -Post free). 

Great Britain, the Colonies, and all Foreign 
countries. 12/6 per annum. 

The Triennial Subscription is 35/- (three years). 
Address remittances to Concrete Publications. Ltd. 



Telegraphic Address : " Concretius London.' 
Telephone No.: 657 7 Gerrard. 



General Offices: 
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Agents.— For Australia: Messrs. Gordon and Gotch. For South Africa: The Central News Agencv, Ltd. 
For Canada: The Toronto News Company and the Montreal News Company. 



286 



l&gSSSS£iK£9 CORRESPONDENCE. 

CORRESPONDENCE. 

Under this heading ive in-vite correspondence. 



REINFORCED CONCRETE FAILURES. 

Dear Sir,— In your editorial notes in a recenl issue under the above heading you 
gave two warnings on the matter of failures in reinforoed concrete work. 

The first one, addressed to the builder or contractor, is undoubtedly one with 
which everybody will agree, and this warning is certainly useful in view of the fact 
that many specialists send out invitations to tender broadcast, and in many instances 
these invitations are received by builders who have had no previous experience of 
reinforced concrete. To add to this warning, I venture to suggest that it would not 
be out of place to suggest to these specialists that they should send with their inquiries 
to builders sufficiently detailed specifications and bills of quantities to enable the 
builders to realise the true value of the work. 

I am sorry to say that many specialists avoid giving details to builders in lh.< 
hope of being able to obtain a cheap price. It is obvious that, if a builder with 
insufficient information gives a price for which he afterwards finds he- cannot carrv 
out the work, the man is tempted to scamp the work. 

Taking the case of a builder tendering for an important job and receiving from 
about half-a-dozen or more firms of specialists offers of schemes and bills of quanti- 
ties, he will undoubtedly price every one of them and incorporate whichever is the 
cheapest in his tender, as he has no means of deciding for himself whether the 
cheapest one is really the best. 

Personally, I think that the danger of failure through this practice is rather large. 

As time goes on and the specialists multiply, it is open for everybody who likes 
to do so to call himself a speeialist, and to invite tenders on this basis in the hope 
of securing a job on which he is paid by royalty, commission, or by selling the 
reinforcement. 

This brings me to criticise the second warning which you issue, and which I 
venture to submit is unfair to those who combine designing and contracting. 

What is practically suggested in this second warning is that if those firms who 
combine contracting with designing have not yet had failures they are likely to have 
them in the future. 

I do not see at all why such firms are more likely to have failures than those who 
simply borrow schemes from independent specialists, and I would say, furthermore, 
that ali failures that I can call to mind in this country have actually happened in cases 
where the specialist was not the contractor. 

What has actually taken place in the last few 7 years is that firms of contractors, 
feeling uneasy owing to the amount of competitive systems that there are, and 
feeling a certain amount of uncertainty as to the relative merits of these systems, 
have actually either retained the services of a competent practitioner or engaged his 
entire services to advise them and to control the reinforced concrete department. 

It should be obvious to the writer of your editorial notes that a firm who under- 
takes the designing and the contracting together undertakes considerably more respon- 
sibility as compared with a firm who goes in for designing only. The specialist 
contractor cannot lay the fault on an outside designer, and the disputes as to whether 
the design is wrong or the contractor is at fault vanish altogether when the whole 
work is carried out by one firm. Moreover, contractors who go to the care and 
expense of organising departments of their own will naturally be firms who have large 
connections and important interests to protect, and have therefore every incentive to 
retain the services of or employ thoroughly capable experts to advise them. 

A.R.I. B.A. 
The Editor, Concrete and Constructional Engineering. 



287 



POPULAR USES. 



(CQNC^ElllJ 



POPULAR USES. 



Under this heading it is proposed from time to time to present particulars of the more 
popular uses to -which concrete and reinforced concrete can be put, as, for instance, in the 
construction of houses, cottages and farm buildings. Previous articles "will be found in our 
issues of December, 1912, and January and March of this year.— ED. 



CONCRETE COTTAGES. 



The following are some notes and particulars regarding a concrete cottage erected on 
Messrs. Rowntree's estate, York, to the design of their architect, Mr. J. Swain, under 
whose supervision the work was also carried out. 

The cottage is an experiment to attempt to solve the question of cheap well-built 
sanitary cottages for agricultural labourers. Mr. Swain writes as follows : 

" Having designed very largely and erected numerous structures in reinforced con- 
crete, I was convinced that if we would build cheaply and well, undoubtedly this is the 




Concrete Cottage, York. 
Messrs. Rowntree's Estate. 



material to which architects will have to look for cheapness combined with durability. 
It must, of course, be borne in mind that concrete work must be well done, and excep- 
tional care taken in the choice of materials and proportions, in order to have good results. 
The general architect is often inclined to look discouragingly on concrete because his 
experience has taught him that in all probability he will be troubled with expansion, 
cracks, and dampness, especially with regard to flat-roof construction. Hut practical 
experience has shown that with the proper selection of materials, and combined with 
Portland cement which will pass in every respect the British Standard Specification, 

there is little bar of these trembles arising. There are two great faults often made in 

connection with concrete work namely, either too great a proportion of cement or too 
little is used. Each particle of aggregate should be thinly coated with cement grouting, 

28S 



' /, eoNyreucnoNAi.' 

L<V ENCUMBERING — , 



CONCRETE COTTAGES. 



and the interstices filled with the smaller proportions of aggregate and not cemented 
together with lumps of pure cemenl as is often the case, otherwise there is sine to 
be difficulty with uneven expansion. Concrete for roots should be composed of gravel 
or the like impervious stone." 

The writer has found the most simple and satisfactory method of obtaining propei 
proportions of aggregate is to pass the gravel through a screen having a circular mesh 
of |-in. diameter, and grading the aggregate down from | in. to pea size. This clean, 
wetted gravel should then lx* put into a bucket, rilling it level with the top, and into 
this a sufficient quantity of water should be poured to fill up the interstices to oxer- 
flowing. The proportion of water necessary to fill the bucket in bulk is the proportion 
of -and to be added to the gravel. Both sand and gravel must be well washed and free 




-o 



Plan 

Concrete Cottage, York. 

from any foreign matter. Having obtained the proportions of sand required to mix 
with the gravel, the best proportion of cement is one to six in bulk. If these instruc- 
tions are carried out, and the concrete thoroughly wetted in the mixing, and kept wet 
for a few days, there is little fear of leakv roofs. The usual cause of unsatisfactory 
concrete work has been due to the contractor taking very little heed of the concrete 
because he intends facing same with a granolithic finish. This must on no account be 
done if good, sound work is to be the result. The architect must insist upon the 
concrete being put down in a thoroughly wet mass, and, when it has sufficiently set to 
allow trowelling, the original surface must be well trowelled with a metal trowel. If 
concrete is allowed to set and is followed on with a rich mixture of granolithic topping, 

289 



POPULAR USES. 



[ CONCRETE) 



a variation of expansion will be obtained, and expansion cracks will occur, and in 
many cases the granolithic will leave the body of the concrete. 

The experimental cottage here described was constructed in every way to pass the 
local bye-laws of York. The external walls are 9 in. thick. There was, of course, no 
necessity to use such a thickness, as the writer has built a two-storey house at the 
seaside where the walls are only -)i in. thick, but the bye-laws of York would not allow 
of any reduction. Blocks were cast in moulds, as shown in the accompanying photo- 
graph. The method of obtaining a rough cast finish was procured by putting a thin 
layer of sand at the bottom of the moulds, embedding into it some sharp, clean basic 
slag, and then about 4 in. of good solid gravel concrete. The mould was then filled up 
with concrete composed of clean, screened boiler ashes. The ash concrete was used for 
two purposes, firstly, because it was cheaper than the gravel, and secondly, because it 
forms a good surface for skimming over with plaster, and prevents condensation to the 
walls. The same course is adopted for the reinforced concrete flat roofs and is worthy 
of comment. When making the slab at least 1 in. of good ash concrete should be put 
down and covered over immediately with the gravel concrete. This gets over any 




Concrete Cottage, York. 
Messrs. Rows-tree's Estate. 

difficulty experw need with extreme variations of temperature. The internal walls were 
made entirely of ash concrete 2\ in. thick, and a mould and sample block are also to 
be seen in the illustration. 

The modus operandi for constructing a cottage adopted by the writer is as 
follows : — ■ 

Strip oil the vegetable soil, and fill in with hard clinker ashes or broken stone or 
other suitable material, lay over the whole of the site a 4 in. concrete slab composed of 
good gravel concrete, bring up the sides the width of the walls to in. above the exist- 
ing earth line. This forms a raft similar to an inverted box lid. Care must l>e taken 
that the whole of the concrete necessary to form this slab and the sides shall be done 
in on<- day to prevent cracks or faulty adhesion. After a couple of days' setting the 
Living of the blocks forming the external walls can be proceeded with. Tiles,- walls, 

which have a very rustic appearance from the outside, have been smoothed off when 
cast on the internal face, so .-is t,> dispense with expensive plastering. In a number of 
cottages it would be quite sufficient to give these walls a coating of lime-wash or 



290 



1 



SSSSBBS'iil CONCRETE COTTAGES. 



distemper, but in the cottage in question the walls wen- lightly skimmed with a coal 
of lime-putty gauged \vi;h plaster of P. -iris. The windows were built in as the work 
proceeded, and the fascia was formed of solid concrete. This was done in ord 
embody small pieces of steel to stretch the wires for the reinforced concrete roof. The 
floor boards come in useful for centering for the concrete roof. 

The concrete roof was composed of gravel concrete carefully graded and mixed six 
to one. The wire reinforcement was then stretched across from side to side, and the 
slab cast 4 in. thick with stiffening beams on the outside so as to dispense with expensive 
wooden forms and also unsightly ceilings. This slab was trowelled after it was properly 
set, and has proved perfectly watertight. 

Ash concrete was placed upon the gravel concrete floors to the necessary thickness, 
and the floor boards were nailed down to the same. When fastening the boards 
to the breeze or ash concrete foundation, care must be taken that the boards bed 
down solid on to the concrete. If the concrete is not perfectly level, fine ash should 
be sprinkled over in order that there shall be no air spaces between the boards and 
the concrete. The concrete must also be thoroughly dry bt fore it is covered with 
boards. Unless these two items are carefully watched, trouble will arise from rot. 
The writer's experience, especially with large factory work, is that, provided the 
concrete is drv and the whole of the air expelled from under the boards, a thoroughly 
sound floor can be obtained. Immediately it is endeavoured to get a small air space by 
inserting strips as is often done, dry-rot will ensue, which spreads very quickly in vi.iated 
air. 

File chimnevs were very carefully worked out to prevent down draughts, by pro- 
viding adequate openings on each side, covered with concrete slab. It is often said that 
low shaft chimnevs will not draw, but no difficulty has been experienced, although this 
cottage is placed in low land at the bottom of an orchard, and is surrounded by tall 
trees and higher buildings. The living room, which is 15 ft. 6 in. by 12 ft. 6 in. is 
provided with kitchen range, and the copper in scullery is built at back of the range 
with specially constructed flue and damper, so that the water in the copper is heated 
by the fire of the range. From the copper a pipe is fixed so that hot water can be 
discharged into the bath. In this case a w.c. was constructed as earth closets are not 
allowed, but the cost given does not include drainage. 

In addition to the living room and scullery above mentioned, the cottage comprises 
a bathroom, one bedroom 11 ft. 6 in. by 10 ft., and two smaller bedrooms, each 9 ft. 
by q ft. There is also provision for coals, and a passage 15 ft. 6 in. by 3 ft. b in. The 
height of the rooms is 8 ft. 6 in. The cost of labour and materials was together 
^,'88 12s. 8d., but it should be stated that no charge has been made for the boiler ashes, 
which were supplied free, and for which is. per load cartage was paid. This cottage has 
been inspected by the Right Hon. Walter Runciman, who expressed great satisfaction 
with the accommodation and appearance. 



2QI 



MEMORANDA. 



(CTCRETEJ 




Memoranda and Netus Items are presented under this heading, <with occasional editorial 
comment. Authentic netus "will be •welcome. — ED. 



BUILDING TRADES EXHIBITION. OLYMPIA, APRIL 12th TO APRIL 26th. 

\\ E have been unable to obtain an advanced copy of the catalogue of the Building 
Trades Exhibition, but we learn that amongst the many concrete exhibits and kindred 
trades, the following firms have obtained space, and will, as usual, be thoroughly 
represented : — 

Art Metal Construction Co., Ltd., 5-11, Holborn, E.G. — Stand No. 104, Row E. 

The Associated Portland Cement Manufacturers 1900) Ltd., Portland House, 
Lloyds Avenue, E.C., will have their usual stand, Xo. 120, Row F. 

R. H. Baumgarten, S, Manor Park, Lewisham, London, S.E., of First Cottbus 
Cement Goods and Machine Works. — Stand No. 128, Row F. 

Bell's United Asbestos Co., Ltd., Southwark Street, S.E. — Stand No. 168, 
Row H. 

Bispham Hall Colliery Co., Orrel, near YVigan. Stand No. 73, Row D. 

British Ceresit Waterproofing Co., Ltd., 68, Victoria Street, S.W. — Stand 
No. 21c, Row J. 

The British Steel Piling Co., Dock Mouse, Billiter Street, London, E.C. — 
Stand No. 7, Bay, in the Gallery, 

The Expanded Metal Co., Ltd., York Mansion, York Street, Westminster, 
London, S.W., have their usual stand, No. 157, Row G. 

General Fireproofing Co., 34-36, Gresham Street, E.C. — Stand No. 95, Row E. 

Homan & Rodgers, 17, Gracechurch Street, E.C. — Stand No. 130, Row F. 

Ironite Co., Ltd., 1, \ 'ictoria Street, S.W. — Stand No. 214, Row J. 

W. Kennedy, 11, Furzeham Road, West Drayton, Middlesex. — Stand No. 43, 
Row C, where demonstrations of rod-bending machines can be seen. 

Kerner, Greenwood & Co., King's Lvnn. — Pudlo waterproofing. — Stand No. 33, 
Row C. 

J. A. King & Co., 181, Queen Victoria Street, E.C. — Stand No. 112, Row F. 
Mack partitions. 

Kleine Patent Fire-Resisting Flooring Syndicate, Ltd., 133, High Holborn, 
VV.C. — Stand No. in), Row F. 

Lewis, Berger & Co., Homerton, N. — Stand No. 59, Row D. 

F. McNeill & Co., Lambs Passage, Bunhill Row, E.C— Stand No. 103, Row F. 

Ozonair, Ltd., 96, Victoria Street, S.W. — Stand No. 17*), Row H. 
The Ransome-verMehr Machinery Co., Ltd., 508, Brunswick House, West- 
minster, Ix>ndon, S.W.- Stands Nos. 218-219, R (| w K, where exhibits of concrete 
mixing machines and steel piling will be on view. 

Reinforced Metal, Ltd., of Glasgow, will have an exhibition demonstrating a 
new form of column construction which will call for considerable attention and create 
great interest in engineering circles. — Stand No. 136, Row F. 

Ruberoid Co., Ltd., 81-3, Knightrider Street, E.C. Stand No. 132. Row ('.. 

G.R. Speaker & Co.. 29, Mincing Lane, E.C. Stand No. 63, Row 1). 

292 



I 



[ S8SS&8SHJ MEMORANDA. 



The Trussed Concrete Steel Co., Ltd., 60, Caxton House, Westminster, 
London, S.W. Stand No. 154, Row G. 

Vibrocel, Ltd., Eldon House, Eldon Street, E.C.— Stand No. 144, Row (,. 

Vulcanite, Ltd., 1 iS, Cannon Street, E.C. Stand No. 105, Row E. 

The (U.K ) Winget Concrete Machine Co.. Ltd., Newcastle-on-Tyne. Stand 
No. 193, Row J. Continuous demonstrations will be held of the " Winget " concrete 
block and slab-making machine, the " Titan " concrete block and slab-making 
machine, and the " Express " hand-power mixer. 

Most of the other well-known firms will be represented, and the exhibition bids 
fair to be as great a success this year as any held in the past. 

Visits to the Exhibition.- By the courtesy prf Mr. H. Greville Montgomery, the 
members of the Institution of Municipal Engineers will visit the Exhibition on 
Saturday, April 12th, at 3.30 p.m., the Exhibition authorities having kindly supplied 
cards of admission. 

Similarly the members of the Concrete Institute will visit the Exhibition on 
Thursday afternoon, April 24th, at 3 p.m. Applications for tickets of admission should 
be made by members to the Secretary of the Institute. 

The British Fire Prevention Committee's Testing Stat ion. — Owing to the 
greater demands made upon the British Fire Prevention Committee for testing facilities, 
il has been decided to enlarge their testing station and to add to their plant. 

The main building is also being rearranged in such a form that the principal 
rooms will be available for the committee's interesting technical and historical 
collections. 

It is anticipated that the alterations will be completed early in April, when the 
testing operations for the new session will commence with several tests of fire-resisting 
doors, various forms of glazing, some new extinguishers, and certain further tests 
with concrete floors, etc., and with partitioning materials. 

Apart from the usual appliances for fire tests emanating from Great Britain and the 
Colonies, there is a marked increase of requests for tests from Germany and from the 
United States, where the Committee's reports also enjoy the recognition of the public 
authorities. 

ERRATUM. 
Messrs. Newhouse's Premises, Middlesbrough. — We regret that the block 
(section) p. 204 of our March issue was inadvertently inserted upside down. 

TRADE NOTICES. 

The Dring Building Block Machine. — This machine consists of a substantially 
built mould box, the sides and ends of which are hinged to a fixed table, and when 
dosed they are held in position by wedge-shaped standards. The machine is simple 
in action. It is claimed that either hollow or solid building blocks with any design of 
face can be quickly and effectively made on the Dring machine ; further, that all 
classes of buildings can be quickly erected with its aid. Some buildings recently 
erected, viz., a pagoda at Wynward Park and St. Mary's Presbytery, Stockton-on-Tees, 
were illustrated and described in our February issue. 

Other buildings erected include a church at Horden, Durham. 

It is claimed that two men can make some 275 to 300 blocks per day, working nine 
hours per day, on one of these machines. 

Illustrated booklets and full particulars can be obtained from Messrs. J. Wilson 
Browne and Son, Ltd., 32-35, Ludgate Hill, Birmingham, who are the sole selling 
agents and licensees. 

Reinforced Concrete Reservoir (Piketiy System*. — The Rural District Council 
of Sedgelleld, Durham, has accepted the tender of Mr. J. W. White, of Sunderland, 
for the construction of the new water reservoir, in accordance with the plans of Messrs. 
Paul Piketty and Co., Reinforced Concrete Engineers, London, W.C. 

CONTRACTS. 
Large Cement Contracts. — We understand that the Associated Portland Cement 
Manufacturers (1900), Limited, have recently completed contracts for approximately 
300,000 tons of Portland cement with eminent English and French contractors I 
in important port works at Buenos Ayres and Mar del Plata in tbe Argentine, am 
Rio de Janeiro. 

29 5 




Q3NCBEaEES3EttE& 



ENGINEERING^ J * 

■*!jf ■— Si 




-§ 1 1 1 § § § %■ 



UNIVERSAL JOIST 
STEEL SHEET IPHILJ 



#* 



€#a 




w 



#§ 



^p^ Illustration shows cross dam at the Entrance to Chertsey Lock which is ^p9 
now being reconstructed by the Thames Conservancy. It is a single row 
of our 15 inch X 43 lb. Piling, and is quite watertight. The same kind 

a a °f P'l' n £ ' s also being used for retaining the sides of the Lock, 

afterwards being covered with concrete and forming part of the ^T" 

permanent work. 

•h THE STRONGEST PILING 4» 
_ ON THE MARKET. 



The British Steel Piling Co. + 



Telephones i 
C-vO HI4 Avenue. 
1414 Central. 

Telegrams : 

'iSSXT"" Dock House, Billiter Street, LONDON, E.C. 
T T 

HI — I — I — I — I — | — § — | — H 



294 



Please mention this /ournjl ruhen xurttinQ. 



k gagSESESS 1 ^ MEMORANDA. 

The Wouldham Cement Co., Ltd., have also, we understand, contracted with 
Messrs. S. Pearson and Son, Ltd., for about [40,000 tons of Portland cement, required 
for tlif new Royal Allien Dock, London, and for the new port works at Va 
Chili. 

CATALOGUES RECEIVED. 

The Spiral Bond Bar Co. Ltd.— A new catalogue recently issued by this 1 
pany has been sent us. The booklet sets forth the advantages of the " Trisec " spiral 
bond bars for reinforced concrete construction. 

The bars are produced by two mechanical processes: first of all, straight bars ol 
special section are rolled, and then the bars are gently and gradually treated until 
they attain a spiral form. Powerful machinery is used for the mechanical process, 
and the operation is so carried out as to avoid injury to the structure of the metal. 

It is claimed thai the spiral form of the bar provides a perfect mechanical bond, 
which is capable of effective resistance to tensile or compressive stress, as required. 

Briefly, the principal advantages claimed are: (1) economy and efficiency; (2) the 
mechanical bond saves the cost of mechanical preparations; (3) higher stresses can be 
employed; (4) high buckling resistance in the case of compression members; (5) reduced 
weight, thus saving freight and cartage, etc. 

The booklet contains many illustrations of buildings where the bars have been 
employed, which include warehouses, grain silos, water-towers, lodging-houses, etc., 
etc. illustrations of the works where the bars are manufactured are also given. 

Full particulars can be obtained from the company at their offices, Caxton House, 
Westminster, S.W. 

The British Steel Bar Co. Ltd. — We have received a catalogue dealing with 
the company's " Helyxa " bar. The booklet briefly explains how these bars, twisted 
in shape, are made, and the various advantages attached to their use are set out. 

It is claimed that these bars have a highly efficient mechanical bond; owing to 
the continuity of the rib running spirally round the bar it carries its full share of stress 
in the structure, i.e., the whole of the steel in the bar carries stress; no fishtailing is 
required ; increased bending resistance is obtained in comparison with the resistance 
obtained from plain and untwisted bars ; a saving is effected in the steel ; lastly, it is 
stated such bars are free from flaws owing to the mechanical process employed in 
manufacture, and they have absolute surface contact with the c ment. Some tests 
made with the bars are reported on. 

Full particulars can be obtained on application to the company at their offices, 
17, Victoria Street, Westminster, S.W. 

ENQUIRY. 

Dear Sir, — I shall be very glad to know if any of your correspondents can inform 
me if it is feasible to construct a reinforced concrete tank which will be able to hold 
pure, clean water practically at boiling point? The tank is to be 13 ft. square and 
10 ft. high. 

I shall be glad if you could give me any information on this subject. 

I am, yours faithfully, 
The Editor, Concrete and Constructional Engineering. ENQUIRER. 

Replies. 

1st Reply. — I have had no experience of the effect of boiling water on 
concrete, but 1 do not imagine thai there would be any direct trouble experienced with 
disintegration of the concrete, as one of the tests for the soundness of cement is for the 
briquette to be immersed in boiling water. 

With such a small tank, 15 ft. square by 10 ft. high, I see no difficulty in making 
it of reinforced concrete, provided the base and sides of the tank are not restrained by 
outside forces, so that contraction and expansion could be taken up without inducing 
stresses on the structure. If, on the other hand, the bottom and sides of the tank 
are restrained in any way, the temperature stresses could be taken up quite well by 
adequate reinforcement. C. P. 

2nd Reply. — With reference to inquiry concerning reinforced concrete tank to hold 
pure, clean water practically at boiling point, 1 consider that it is quite feasible 
construct this, although I do not know of any example in practice of a similar r 

290" 



MEMORANDA. 



CgNCKET E) 



Com rote should not be affected or damaged by boiling water if the cement is of the 
right quality and proper precautions are taken in the execution of the work. I should 
suggest that the reinforcement be in the form of several small bars in both directions 
in preference to a comparatively few bars widely spaced. The work should also be 
allowed to stand for the maximum period of time after execution before being put into 
use. The concrete should be a rich mixture, and the best aggregate would be a clean 
ballast. A. L. 

yd Reply. — I have not had any experience of concrete being subjected to the con- 
ditions mentioned in the above inquiry, but from experience with high drv temperatures, 
providing the concrete was properly made and properly reinforced, a drv heat of 
2i2° F. should not affect it, but after some period it is possible the concrete may com- 
mence to disintegrate with a wet temperature of 212 F. It is presumed that the tank 
would be open or that the steam would have free exit. I think, however, the principal 
trouble would be found at the water-line, where the concrete below and above the water 
would be subjected to such entirely different conditions. A. H. S. 



MISCELLANEOUS 



Rate:— 6 lines (or under), 5s. ; each ad 
T'HE OWNER of BRITISH PATENT 
J- No. 6607 of 1909. entitled " Improvements in Blocks 
for Reinforced Concrete Floors." granted to F. Schiller, 
is desirous of disposing cf the Patent or entering into a 
w rking arrangement under license with firms likely to 
be interened in the same. In the alternative the owner 
would be open to consider proposals to manufacture the 
invention to fill any requirements of the market in Great 
Britain on terms to be arranged. The Patent cover-, an 
invention interesting to Builders, Contractors and ethers 
employing Reinfo ced C- ncrete. Detailed information 
as to the inven ion will be found in the Patent Specifi- 
cation, of which a copy will be supplied to any interested 
party on request. Full particulars can be obtained from 
and offers nude (for transmission to the owner) to 
Marks & Clerk, 57 and 58 Lincoln's Inn Fields, 
London, W.C 



iitional line, 10e7. Remit with order. 

CONCRETE BOOKS at GREAT REDUC- 
TIONS.— New Books at 25 per cent, discount. 
Books on Concrete, Engineering, Building Construction, 
Technical and all other subjects supplied. Sent on Ap- 
proval. State wants. Send for Lists. Books purchased — 
W. & G. FoyLE. J21 Charing CrossRoad, London, W.C. 



Vy ANTED, CEMENT CONSULTANT. 
* » A Cement Manufacturer willing to take a seat on 
the Board of Directors preferred. — Address, Pox No. 1+9, 
Concrete & Constructional Engineering, N' rth 
Brit'sh & Mercantile Building, Waterloo Place, Pall 
Mall. S.W. 



BRITISH IMPROVED CONSTRUCTION CO. 

Telephone: 4067 Victoria. LTD. Telegrams: " Biconcrete, Vic. London." 

"BIC " 
47 VICTORIA STREET, WESTMINSTER, S.W. 

Manufacturers of all kinds of 

Concrete Constructional Materials 

(Plain or Reinforced) 

Including PIPES, PARTITION AND PAVING 
SLABS, SLEEPERS, STANDARDS & POWER 
TRANSMISSION POLES, HOLLOW BEAMS 
AND FLOORS, FENCING POSTS, etc., etc., 
by the well-known "JAGGER" PROCESS. 

Engineers and Contractors Own 'Designs carried out to order 

SPECIALITY. — Reinforced Concrete Pipes for High Pressures, abso- 
lutely Impermeable. Our Concrete weighs 156 lbs. per cubic foot. 



296 



Please mention this Journal "when ivriting. 



CONCRETE 

AND 

CONSTRUCTIONAL ENGINEERING 



Volume VIII. No. 5. London, May, 1913. 

EDITORIAL NOTES. 



BUILDING TRADES EXHIBITION. 

For all interested in building construction and structural engineering, the event 
of last month has certainly been the great Building Trades Exhibition at 
Olympia, which has been eminently interesting and again indicated what fore- 
thought, careful organisation, and a definite purpose can achieve in exhibition 
management. 

In one or two directions, however, we should like to make some sugges- 
tions. First of all, having regard to the dearth, of new inventions or so-called 
novelties in the Exhibition, it might be advisable to hold the Exhibition only 
once in three years or every four years. We believe that many of the exhibitors 
would be quite prepared to even pay a higher rate for their space if a somewhat 
longer interval intervened, and both the visitors and the exhibitors would 
probably appreciate the change, which need not mean any great pecuniary loss 
to the Exhibition management if the space rates are proportionately raised. 

Secondly, we think the management should rather discourage large paint 
exhibits, which, however handsome in themselves and at this particular Exhibi- 
tion quite exceptionally beautiful in certain cases, are in reality rather 
monotonous and uninteresting ; and as the management is in that excellent 
position of being able to pick and choose its exhibitors, it might be better to 
allot more space to the really interesting exhibits and give these displays of 
paint work a lesser superficial area. 

Thirdly, regarding the general characteristics of the Exhibition, we fully 
realise the difficulty of enforcing regulations as to the character of the Exhibition 
stands, and the absence of onerous regulations cum competition has certainly 
led to a vast improvement in the stalls ; but we certainly think there should be 
a limit of height both as to minimum and maximum. There was one very 
handsome exhibit housed in a half-timber house near the main entrance that 
largely spoilt the vista of the whole ; and, on the other hand, there were certain 
exhibits on island sites which were not sufficiently pretentious and rather spoilt 
some of the principal points, to which more prominence should have been given. 

Another suggestion that would make for more prolonged visits by the 
older and perhaps more influential visitors, on whose specification the exhibitors 
largely depend, is the provision of ample chairs and seating accommodation on 
the main floor of the building. There was some attempt at this in the annexe, 

b 297 



BUILDING TRADES EXHIBITION. [CONCRETE] 

but it should be remembered that man}- of the class of visitors who are really 
useful to the Exhibition have a distaste for sitting in tea or refreshment rooms 
and yet find a prolonged visit to the Exhibition too tiring- without the facility 
for rest at intervals. Exhibitors themselves would also do well to have a more 
ample provision of chairs on their stalls if the}- wish to explain their systems and 
specialities at leisure to some of the older members of professions primarily 
concerned. 

As far as the purely structural exhibits are concerned — i.e., steel frame 
construction, concrete and fire-resisting construction, other than brickwork — 
we were somewhat disappointed at the rather limited number of exhibits in 
this particular section, and we all too fully realised that the concrete or 
reinforced industry had not made proper use of the very excellent opportunity 
afforded it, which we think to the detriment of its advancement. We have 
inquired very carefully into the reasons for this, and have come to the conclusion 
that this is partly due to the difficulty of obtaining suitable space for substantial 
displays, and, above all, to the limited time available for the preparation of 
exhibits of a structural character ; and we thus venture to suggest whether the 
time has not arrived for arranging for outdoor exhibits, for which suitable space 
could be devised under temporary shelters both in front of the main facade and 
at the side. 

We trust this matter may have the careful consideration of those interested 
in the subject, for we believe it would be eminently beneficial to those industries 
in which this journal is primarily interested if outdoor exhibits could be arranged 
for. 

With the Exhibition itself we deal in a special article, and in conclusion we 
would again congratulate the principal organiser thereof, Mr. H. G. Montgomery, 
J. P., for the really model lines on which the work is organised and conducted. 

THE IMPENDING INTERNATIONAL ROAD CONGRESS. 

We should like to take this opportunity of reminding our readers of the 
International Road Congress which is to take place in London in June 
(June 23rd to 28th), inasmuch as the problem of utilising concrete and reinforced 
concrete in road construction is a matter which is coming largely to the front 
and is finding experienced advocates both in the United States and on the 
Continent of Europe. 

We have the unfortunate name at present in this country of lagging behind 
in matters relating to the careful consideration of the uses of concrete and 
reinforced concrete, and it might be well if, for once, an exception were made 
by us in taking the lead in the matter of investigation and research as t:> the use 
of concrete in road construction, seeing that there is no country where roads 
could be more economically and practically constructed of concrete than in 
England, and that this type of road is particularly suitable for our increasing 
commercial motor traffic. 



>. 9 S 



E 



, CONSTPIKTIONA1. 
E.N(.INtXBlNG — , 



THE MIDDLESEX GUILDHALL 



si] 





THE MIDDLESEX 
GUILDHALL. 



By ALBERT LAKEMAN. 



The building here described is mainly of steei, ana reinforcea concrete onlv plays a minor 
part in the luork, but there are many features of particular interest in the construction. — ED. 



This important building has been erected from the designs of Messrs. J. S. 
Gibson, Skipwith & Gordon, on the site of the old Guildhall, close to West- 
minster Abbey, and it has an area of about 17,150 sq. ft., with a frontage of 
102 ft. to Broad Sanctuary, facing the Abbey, and 160 ft. to Little George 
Street; while practically all the offices are lighted from the adjoining streets, as 
the site is an island one. The southern portion of the site has been covered for 




Fig 1. View showing Steel Construction. 
The Middlesex Guildhall. 

several centuries by buildings devoted to the administration of justice, and in 
the new building it was absolutely essential to provide accommodation for the 
work of the Quarter Sessions of Middlesex, in addition to the chambers and 
offices necessary for carrying on the business of the Middlesex County Council, 
and the fact obviously governed the planning and design. The old Courts <>t 
Justice, which were demolished for the execution of the new building, were built 
towards the end of the eighteenth century, and the offices for the Mid. Ik- ; 

B 2 299 



ALBERT LAKEMAN. 



[CONCRETE] 



County Council were erected about seventeen years ago, but the reconstruction 
x>f the whole of the building- was necessary owing to the large 



increase in the 




\ c . 

staff and the work of the officials, consequently the present scheme was decided 
upon in 1910. 

An interesting discovery was made during the excavations by tin 

300 



ic contrac- 



f » r CONSTUTJCnONAl.1 
L**ENGTNtXKlNG — J 




?^m 



7^* 



m 



^^~ 



;>Zzz& 



' CT. ; ■'<-/y i 






ilil 



c ffi#%af 



T7-7T L 




77/ £ MIDDLESEX GUILDHALL 

tors, who exposed a heavy rubble concrete raft, which 
appears to have been the foundation of the isolated belfry of 
the Abbey, erected about 1249-1253 and destroyed about 
1700. This old belfry took the form of a .tone tower, which 
was 60 ft. high, and finished with a leaded spire. The raft 
was about 80 ft. by 70 ft. in area and 5 ft. thick, and, curious 
to relate, was carried on elm and beech piles closely spaced 
and about 10 ft. long-, although the soil below the raft was a 
very good ballast. 

The new building- is five storeys in height, giving a 
dimension of 50 ft. from the pavement level to the lop of the 
main external walls, while the top of the parapet of the tower 
is 108 ft. above the same level. A basement floor is con- 
structed below the pavement, and the greater part of this is 
allocated to the Prison Department, there being about 100 
cells with accommodation for warders and wardresses and 
police, and also several witness rooms. The remainder of the 
floor is occupied by the heating and ventilation chambers, and 
tlie numerous record rooms, which are brick-vaulted and con- 
structed with due regard to the safe storage of the valuable 
records belonging to the County Council. 

The ground floor is utilised for the courts, of which there- 
is a large one situated in the centre of the building, entered 
directly from the large vestibule and lighted from two internal 
areas ; and a smaller one situated at the north end of the 
building; both these oourts extending through the height of 
two floors. In addition to> these courts there are offices and 
private rooms for members. The first floor is devoted to 
committee and private rooms, and on the second floor the 
council chamber is planned to come over the larger court 
mentioned on the ground floor, and this council chamber 
provides accommodation for about no members and officials. 
A large ante-room is situated on the east side of the council 
chamber, and the remainder of the floor and also the third 
floor is given up to offices. The whole of the elevations are 
in Portland stone, and they have been designed in the Gothic 
style, which is in harmony with the environment of the 
budding. The composition and detail of the building is very 
successful, and the tower — which is an important feature in 
the design — is happily proportioned, and adds additional 
interest to the scheme. 

The construction of the building is executed generally 
with steel weight-carrying members, with floor panels of tile 
and reinforced concrete ; while the foundation to the tower is 
formed with a reinforced concrete raft, 3 ft. thick, designed 
by the Trussed Concrete Steel Co., on the Kahn system 
This raft carries the six stanchions which support the to 
the load from which, including floor loads, amounts to al oul 

^01 



ALBERT LAKEMAX. 



[CONCRETE] 



i, 800 tons, and this was distributed over sufficient area to give a pressure on 
the soil not exceeding two tons per foot super. The reinforcement generally 
consisted of i-in. Rib bars. 




A typical framing plan is illustrated in Fig. 2, which shows the steelwork 
at the ground-floor level. Generally speaking 1 , the ends ol the main beams are 

302 



f ir con^tcuctionaD 

\K ENOrNEERlNG — J 



THE MIDDLESEX GUILDHALL 



carried by piers where they come againsl the external walls, and stani hions ;i 
columns are only employed in the interior of the building. A large number 
compound girders were used, and these were built up with rolled steel joi 




Fig. 5. View showing Floor in Course of Construction. 




ii. View showing Completed F 

The Middlesex Guildhall. 



plates, to give as shallow a section as possible. There were no excepti 
spans or loads, owing to the straightforward plan, the longest span on 

3°1 



ALBERT LAKEMAN. 



[CONCRETE] 



drawing- illustrated being about 24 ft., and the largest compound girder 2j in. 
by 18 in. over all. In the interior of the building columns and stanchions were 
used, and the latter are of the compound type, built up with rolled steel sections 
and plates, these in some cases resting on small grillage foundations, which 
were carried by the reinforced concrete raft. 

The floor panels are constructed on the patent " Bigspan " svstem by 
Messrs. Diespeker, and these are calculated to carry a superimposed load of 




1 ; i 

Fig. 7. Section. 
The Middlesex Guildhall. 



ijcwt. per sq. ft. A section showing this type of floor is given in the illustra- 
tion in Fig. 3, and it will be seen that hollow tiles are used, these being aboul 
10 in. wide and 6 in, deep. These tiles are temporarily supported on planks 
during the construction of the floor, and the sides of same form the centering 

for the small reinforced beams, which are about J in. wide, with one rod on the 

lower surface in the centre of the span, and in addition one bar on the upper 

30+ 



THE MIDDLESEX GUILDHALL. 

surface to provide continuity where adjacent to the main steel beams. 
are kept in position during concreting by the steel clips which pass round the 
reinforcement and are bent down at the top ends to rest on the tiles, as 
these also giving provision againsl shear. About 2\ in. of concrete is plai 
top of the tiles, giving a total thickness to the floor of 8i in. The photographic 
views show the floor construction during- progress, and some of the hays have 
a width of i<> ft., thus showing the possibilities of this system, which is light 
and eminently fire-resisting. The roof construction is executed generally with 
a shaped frame, built up with rolled steel joists, which can hardly be desig- 
nated as an ordinary roof truss; but the roof over the Council Chamber is 
carried by two steel trusses, which have a span of yi ft. 6 in., and these support 
5~in. by 3-in. rolled steel purlins at 3-ft. centres. These purlins carry the 
concrete slabs, which in turn are covered with slating. The trusses have a 
principal rafter formed of two 6-in. by 3^-in. by i-in. angles, while the ties and 
struts are formed with two 2^-in. by 2^-in. by \-\\~\. angles. The ties have a rise 
of 6 ft. 3 in. at the centre of the span, and these are built up with two 6-in. by 
3-in. by .V-in. angles. The adoption of the method mentioned for the roofs 
generally allowed practically the whole of the space within the sloping portions to 
he utilised for rooms, which would not have been possible with ordinary roof 
trusses. 

The building is heated on the vacuum steam system, and the courts, council 
chamber, committee and ante-rooms are ventilated and heated on a Plenum 
svstem. There are two drainage systems, the rain water being dealt with at 
the basement ceiling level and carried directly to the sewer ; while the soil and 
waste water drains are carried to a pneumatic ejector which raises the drainage 
from the low level to a sufficient height to discharge it into the sewer. The 
general contractor for the work was Mr. James Carmichael, and the steelwork 
was executed by Messrs. Redpath, Brown & Co. The floors were carried out by- 
Messrs. Diespeker, and the reinforced concrete raft by the Trussed Concrete 
Steel Co. 



ALFRED FY SON. 



[CQNCRETFJ 




H 



REINFORCED CONCRETE 
BEAMS. 

ON THE RESISTANCE OF BEAMS 
SUBJECTED TO FLEXURE, 

(I) SOLID RECTANGULAR BEAMS- 
SUPPORTED ENDS FREE. 






By ALFRED FYSON, M.Inst.C E. 

The folloiving is the first of three articles prepared by the Author, on the 
above subject, and should claim the attention of all interested. — ED. 

Introduction. 

The method employed for determining the moment of resistance of a reinforced concrete 
beam which now finds most favour with writers on the subject, and one also which 
appears to be most generally practised in constructional work, is the simple one of 
supposing all internal longitudinal tension to be resisted bv the reinforcement, the value 
of the concrete for such stress being ignored. One of the reasons for thus neglecting 
the tensional value of the concrete is the striving after so-called " simplicity "j another 
reason is due to the little knowledge possessed as to its behaviour at comparatively 
small strains, and a total lack of knowledge as to its behaviour at great strains. 

The fact that an important element of a beam is thus theoretically eliminated whilst 
it is of necessity physically retained, precludes any possibility of rational or scientific 
treatment, as the premises on which such treatment is to be based must be more or 
less false. 

Instead of there being produced some rational theory founded on exact principles for 
determining the value of the moment of resistance, there are substituted certain assumed 
conditions which are made to serve as bases for the arithmetical computation for such 
purpose. 

Some of those assumed conditions are as follows : — 

" The modulus of elasticity is supposed to be constant for both compression and 
tension in the same material ; consequently the stress is directly proportional to the 
-train." 

" The value of the tensional resistance of concrete being considered comparatively 
small, all such resistance is supposed to be taken up by the reinforcemen.t ; consequently 
the position of the neutral axis must be determined solely by the value of the concrete 
in compression and that of the reinforcement in tension." 

" The theory of ' the conservation of plane surfaces ' is to be observed ; consequently 
all internal strain is uniformly varying." 

Now, with the exception of the Las1 condition — and with respect to that it must not 
be inferred thai all internal stress is uniformly varying- -the others as -et forth and their 
.1 rollaries are nol strictly true for small stresses and .strains, and are not even approxi- 
mately true for maxima limits usually adopted in practice. Bui il is claimed for such 
and similar conditions arising from them, that whatever departure from accuracy they 
may occasion or whatever failings they may possess separate^ or combined, errors due 
to such causes will be in the nature of excess of strength beyond thai demand, d. 

With a view to tesl the validity of such claim, the following investigations have been 
undertaken. The laws which govern the theory of elasticity and flexure as generally 
accepted for homogeneous materials will form the basis for rigorous mathematical 

7, Of) 



Bfllgglilgjj l REINFORCED CONOR El E BE \MS. 

treatment. Equations will be deduced for the method which excludes the \ iluc of t 
concrete in Nn>iim ; other equations will be proposed fur the method which includes the 
value of the concrete in tension. A beam of some definite dimensions will I*- ci I 
by both methods, and the resulting numerical details will furnish practical mean 
comparing them. 

In order to distinguish herein between these tun diverse methods, that which 
excludes the value of the concrete in tension will he termed a theory of " Partial 
exclusion," and that which includes the value of that material in tension will be termed 
a theory of " Complete inclusion "; the terms " exclusion " and " inclusion " having 
reference to the horizontal components of the internal resisting forces. The principal 
explanatory data and symbols to be employed are as follows: — 
All linear dimensions are in inches. 
All loads in lbs., and stresses in lbs. per sq. inch. 

All strains are in fractions of one inch, or proportion of the length involved. 
Generally the subfix designates the symbol as affected by compression. 
B, H ^respectively the breadth and depth overall of a beam. 

D = depth from compression surface of beam to the axis of reinforcement. 
V= effective depth of concrete, i.e., its unruptured depth. 
f'ot Fo = some desired or permissible unit stress on the concrete in compression. 

F =unit stress in tension on the concrete at its extreme outer surface. 
F s , fs- some permissible or deduced unit stress on the reinforcement. 
Ec, £ c =siHiie specified or actual modulus of elasticity for concrete in com- 
pression. 
E s ='the modulus of elasticity of the metal constituting the reinforcement. 
d i'o h = positions of the neutral axis of a beam with respect to the extreme 
outer compression surface. 
<f, Vj Ji — positions of the neutral axis of a beam with respect to the axis of 
reinforcement. 
Mr Mr Mr = moments of resistance of a section as allocated herein. 
a s =the sectional area of the reinforcement. 
<r T <j\ =the " elastic " strain for compression on the concrete due respectively 

to Fo and F„. 
X T \\ =the " elastic " strain for tension on the concrete at its exterior surface. 
i) V = ,, ,, ,, ,, tension on the metal constituting the rein- 

forcement. 
Other symbols, etc., will be found duly set forth as occasion may demand them. 
With respect to the symbols d, do ; v, v„\ h, h„\ those under d refer to beams in which 
the tension on the concrete is entirely neglected; those under v refer to beams in which 
the concrete is capable of resisting, and is supposed to resist, tension over some par- 
ticular depth as defined by V; those under h refer to beams in which the concrete 
remains sound and unimpaired between the extreme upper and lower surfaces of a 
beam, the depth over all of the concrete thus becoming available for purposes of 
internal resistance, 

By the term " strain," which will be frequently used in these investigations, is to 
b • understood the longitudinal alteration of length due to force acting in the same 
direction; and by " stress " is meant the intensity of the internal resistance offered to 
such force. 

The Theory of Resistance to Flexure 
The generally accepted hypothesis respecting the theory of the internal resi 
i beam at a section as due to flexure may be briefly considered in the followii 
manner : — 

Let Fig. j represent part of the side of a rectangular beam of uniform s 



ALFRED FYSON. 



[CONCRETE! 



loaded in such manner that it is bent downwards, so that a constant bending moment 
exists throughout its length ; thus only the action of the horizontal stresses and their 
corresponding strains will have to be considered. Let the moment of resistance of all 
the internal forces at the section a a on the vertical line Y Y be required. Assume an 
elementary strip bounded by the planes Y Y and Z Z 0j its depth and breadth being of 
the same dimensions as for the beam, and its length unity, or, sav, i inch. 

Flexure causes the top of the beam to become compressed and the bottom to become 
extended, therefore the elementary strip is shortened some amount c T at one extremity 
and lengthened an amount \. at the other extremity of its depth. 

Join the two points b and b, so found by the straight line b ft representing the 
side of a plane surface through the beam. The original section a a on the line Y Y 
has gone through an angular movement and has shifted to the position b„ b, the only 
point which has not moved being at O, where the two sections cut each other; this point 







z„ 


i 


<v- 


a. 








o 


[LINt OF NE.UTRAL- 


AXIS \ 


* 

i 

si 
° t 


T T 
I 1 

1 1 
i i 


■\ri-J 


X 




JRE.INFORCLMLNT 




\ i 
\ 1 


QI 
I i 
I 1 
a , 


'. 'V.'! 






j 




!\ 


* 


,'.«;;» 








2 




a 


«— At— * 









>- 

FIG. I 

O is at the neutral axis of the section a a . It will be noticed that the inclined line 
b b has, by construction, been made a straight line; this is in conformity with what 
is termed " The theory of the conservation of plane sections," the meaning being that 
an originally plane section before bending remains plane during and after bending. 
Such a theory, however, can only be supposed to apply to materials which are perfectly 
elastic or in which the " set " has been eliminated or is so small that it need not be 
considered, and in such sense only will it be accepted in these investigations. 

The actual longitudinal strains now imposed on the elementary strips between 
Y Y and Z Z are indicated by the ordinates of the two triangles the perpendiculars of 
which are represented by the lengths <j t and X T - Corresponding with these strains 
are their stresses or internal resisting forces, and these — including the " tension 
resistance of the reinforcement due to the extension v — do not vary in the same manner 
as the strains, but only in accordance with the relation between stress and strain for 
the particular materials employed, and that relation is never in direct proportion for any 
elastic substance. Within certain low but varying limits, however, the relation between 
stress and strain is generally assumed to be in nearly direct proportion for most materials 
of construction, and such proportion is generally known as Hooke's law. In order to 
define the exact position of the point O in the line Y Y n a condition of internal static 
equilibrium must be observed. Supposing the internal resisting forces or stresses "I 
compression and tension to be represented algebraically as of opposite signs, that con- 
dition is expressed thus : the sum of the stresses must equal nothing. This, according 
to Fig. i means that the stresses <>f compression and tension due to the -strains of 
shortenings .and lengthenings in the two triangles hounded by the planes d and 
b b musl be equal to or balance each other. 
308 



s 



» COTMSTPUCTIONAE 
ENGINEERING — , 



REINFORCED CONCRETE BEAMS. 



From the point draw in opposite directions the straighl lines <>. OX eacli 
normal to the line V V „ : the line X OX becomes a side of the plane of the n< 
of the beam, its depth from the top of beam being designated by tin- symbol /;„. 

The moment of resistance at the section a a a is found by adding together the 
products of all the internal normal foroes and the distances of their respective centres 
of resistance from the neutral axis at O. 

Mathematical Determination of the Moment of Resistance. 

In the diagram Fig. 2 let X Q OX be the axis of strains, and YO Y that of -tresses, 
and suppose 0b o bo to be a compression stress-strain curve for the concrete composing 
the beam. The part of the diagram above the axis X OX is to hi- allotted to compres- 
sion and that below it to tension. In the first instance the concrete will be considered 
separately without reference to the reinforcement, and in all cases of strain it is to bo 
understood that " clastic " strain is meant unless the " set " is specifically mentioned. 




FIG. 2 



Let <r T be the measure of strain or the shortening of an elementary strip due to some 
particular or desired stress F„ in compression. Let the distance a b as an ordinate to 
the curve 0K>b\] , denote "V ; through a„ and b draw a line parallel to X o 0X and pro- 
long it in each direction. That line may be assumed to represent the top of the beam 
shown in Fig. 7, and the distance 0a„ may be assumed to represent its depth for the 
part in compression. From the point b a draw a straight line through and prolong it 
into the part of the diagram allotted to tension to some point b. The straight line b o 0b 
is supposed to illustrate the " Theory of the Conservation of Plane Sections." Through 
b draw a line parallel to X„OX, cutting the axis Y0Y o in the point a; that line, 
prolonged in each direction, may be assumed to represent the bottom of the beam 
Fig 7, and the distance Oa the depth of the part in tension. The measure of strain 
or the extension ab of the elementary strip is denoted by K, which is a known or 
measurable quantity. With Oa as axis of stresses, construct the tension stress-strain 
curve Ob" b for the concrete composing the beam, so that it passes through the point I 
already given, the point being the origin. The ordinates to the stress-strain curv 's 
Ob K b and 0Kb o must be drawn to the same scale, but owing to the fact that t 

3°9 



ALFRED FY SON. 

curves are never exactly alike for the same material, the scales for the tension and 
compression stresses on the axis YOY„ cannot be the same, but it is not necessary to 
consider here their relative proportions, as the diagram is only intended for practical 
illustration. 

The effect of Flexure is to cause alterations of form in the stress-strain curves ; 
thus the curve 0bol< o moves up to and coincides with the straight line 0b o , and the 
curve Ob'b moves up to and coincides with the straight line Ob '. the curves of strains 
now become straight lines, and their corresponding stresses can be graphically repre- 
sented as shown by the curves Ocl,c and Oc'c. 

The following method of plotting the curves of stresses on the bases Oa„ and Oa 
may be found instructive : — Take, for instance, the compression stress curve 0c" o c n — 
At some stress /„ on 0a o , the corresponding strain on the curve Ob" b„ is °". When 
the curve Obob coincides with the straight line Ob„ the strain a becomes augmented 
by an amount </ — the difference between the ordinate to the straight line and that to 
the curve at f„ — -and these two strains c + c' correspond with the stress f and the 
augmentation f due to <j\ This new stress /0+/0 being plotted as an ordinate to a 
curve at f„ on the base 0a o determines a point in the required curve of stresses ; other 
points being found in a similar manner and joined, the complete curve of stresses 
OcoCo is formed. The tension stress curve Oc'c on the base Oa can be delineated in a 
similar manner to that just shown for compression. Now if the point b has been 
correctly chosen on the tension stress-strain curve, the sum of the stresses within the 
figure Oc'ca will be equal to the sum of those within the figure 0coC o a o , and the 
condition of internal static equilibrium will be observed ; in such case the position of 
the plane of the neutral axis in the beam will be defined by the relation that 0a o bears 
to Oa each as a linear dimension, and not by the relation that F v bears to F as stresses. 
It will now be convenient to substitute for some of the symbols in Fig. 2 others 
which have special reference to the physical proportions and necessarv details connected 
with the proposed beam which will come under consideration. 

In general construction, let Fig. 3 (See page 3/3) be similar to Fig. 2, with the 
addition of the reinforcement which is now to be included. 

The total depth of the beam is H, and the depth from its top to the axis of rein- 
forcement is D, which is the sum of two parts; v, the distance from the axis of rein- 
forcement to the neutral axis, and v , the distance from the neutral axis to the top of 
the beam. 

The vertical distance I* is the depth from the top of the beam to the point in the 
mass of concrete which is effective for purposes of horizontal resistance. Thus, if a 
crack or other similar defect appeared (as shown in the diagram), the depth or vertical 
extent of such rupture or defect, H—V = q, would be ineffective, and only the depth, 
V — v = u, would be effective for purposes of calculating the resistance of the concrete 
due to tension. 

Theory of ' ' Complete Inclusion. ' ' Derivation of the Equations. 
The equations now to be proposed will mainly be based on some desired stress, 
F , in compression; they will also depend on the depth, v , of the " compression " part 
of the concrete, the effective depth, I', of the concrete, the depth, P. of the reinforce- 
ment below the top of the beam, and the relations between stress and strain in the 
reinforcement, and in the concrete. 

It is required to formulate equations so as to determine the moment of resistance 
at tlie section a0ct o , Fig. 3, in accordance with the various conditions appertaining to 
this method in which the whole value of the concrete is utilised, and to this cn<,\ means 
must be established whereby the relation between stress, strain, and their connections 
can l>e established. 

Apparently an equation which will accurately define the precise relation between 
31c 



Elllgglg3 REINFORCED CONCRETE BEAMS. 



Stress and strain for any natural material has yet to be promulgated; but one which 
will, within certain limits, define such relation with fair accuracy is that which i-; 
generally termed an exponential form of equation, as follows : — 
i j 

<r=Cj for compression and \ = A'/ 1 for ten ion, 

where m, n, C anil K are coefficients to he determined by the particular nature of the 
material under consideration. 

Such equations, which have already been used by some Continental writers, do not 
and cannot be made to express accurately any stress-strain curve throughout its entire 
range, to whatever degree of refinement the exponents m ami n, or the coefficients C and 
K may be chosen; but beyond low stresses and strains and up to the ordinary working 
values usually obtaining in practice, they can be made to give results which will agree 
very well with those derived from experimental tests. 

In Fig. 3 the curve Otv represents the " compression " stresses acting on the 
depth v , some definite stress F being a known limit. Any other stress f at the 
distance y from the axis X OX can be found in terms of F from the following 
expression: / = F>'Y" (1) 

Thus when y„ is equal to v then /„ becomes F„. 

The direct relation between stress and strain is thus expressed. 



/-(c)"' 



/<r\m\ (2) 

whence Fo= \r) ) 

The stresses in tension on the concrete are represented by the curve Oc'c, and the 
depth over which those stresses extend is denoted by u. In the first instance, the 
concrete will be supposed to be sound from top to bottom, and therefore effective for 
tension from the neutral axis to the bottom of the beam, so that q = o andw=if — v - 
Any stress /at the distance y from the axis X OX can be found in terms of F from the 
following .expression : — - , T Vv\" 

f= %) ^ 

The direct relation between stress and strain is thus expressed : — 



/-■(*>"! 



it fM*l (4) 

whence _p=l_r_j ) 

The numerical equivalents of the exponents in and n and of the coefficients C and 
K may be any positive quantities, whole or fractional, which will best suit the purpose 
for which they are required. 

Hitherto the relation between stress and strain has been represented by a curve 
called the stress-strain curve, but within certain limits such relation may be expressed 
by a numerical constant termed the " coefficient " or " modulus " of elasticity. This 
modulus is often practically stated in a very vague manner, so that in one case it may 
be due to the " total " alteration of length of a test-piece, resulting from the direct 
ai tion of a known stress or force; in another case it may be due to the "elastic" altera- 
tion of such length from a similar cause; and in yet others it may be due to some 
alteration of length between those two extremes. In reality only the " elastic " change 
of length ought to be understood, and in such sense it will be employed here. For 
materials in which the modulus of elasticity — it is sometimes not improperly called the 
modulus of stiffness — is approximately a numerical constant such a method of com- 
bining the relation between stress and strain has considerable advantage. Un- 
fortunately, however, so far as exact science is concerned, the coefficient of elasti< 
never a constant for any material; but for practical purposes it is generally ass 



ALFRED FYSON. [CONCRETE] 

that no great error is committed by supposing it— usually denoted by the letter E— to be 
a numerical constant up to some fairly well-defined limit of stress, and differing in 
value only with the differing material it is supposed ti> represent. The coefficient express- 
ing this modulus of elasticity i- stated thus by Rankine :— 

E= (i) 

longitudinal pliability. 

In some metals— especially iron and steel— the stress and strain vary in nearly 
direct proportion almost up to the limits of ordinary working stresses, and such propor- 
tion of uniformly varying stress will be accepted here. Thus for steel, which metal will 
constitute the reinforcement, the coefficient stated in lbs. per sq. in. is — 

E s = ^ (5) 

In (5) the modulus of elasticity E s is found in terms of f s and v- fs being the 
intensity of stress to be here computed at lbs. per sq. in., and 77 the alteration in length 
due to that stress on a prism of the metal originally 1 in. in length. The result of all 
the internal forces acting in combination at the section aa Fig. 3 — giving the moment 
of resistance at that section — is thus determined. 

The forces in compression, comprised within the area Oc" c ao Fig. 3, are to be 
denoted by A . 

The forces in tension on the concrete within the area Occa are to be denoted 
by A . 

The forces in tension, due to the extension 77 of the reinforcement, are to be denoted 
by A s . 

It is necessarv to determine the exact position of the neutral axis at O in the section 

aa . 

The condition with respect to the equality of the forces on either side of this point 
has alreadv been laid down, and in symbols is as follows : — 

A = A+A S (6) 

The forces in (6) are to be separately determined, the breadth B of the section being now 
included in the equations where necessary : — 

The forces in compression A , or the product of the area OcoC a and B : 

A o =BJfoSy (ii) 

Substituting for / its value in (1) — 

_BF f y o= v o BFp yo ' + '" , m) 

Making y o =v Then A = BF » V ° (7) 

The forces in tension A— in the concrete only— or the product of the area Oc\a 
and B : — r y=u 

A=Bffs y (iv) 

J >=o 

Substituting for f its value in (3)— 



4=^ /'l7 Sy= BFy^ (v) 



_. . BFu i..\\ 

Making y = ». Then A— — — VV1 ^ 

For the concrete in compression, F is a known quantity; but the unit stress ot the 
concrete in tension F is not known, and it must be put in terms which are or can be 

known. 

312 



ro.CONSTRUCTlONAIJ' 
I f V ENfil^fcF-KlNO — J 



REINFORCED CONCRETE BEAMS. 



In Fig. 3 the triangles Ob a and 0b„a o are similar, therefore the f< 11 
holds: — ^r'.u: '.ffr'-Vo (vii) 

whence -V (vm) 

Substituting this value for \ T in equation (4), it is found that — 

(ix) 

In (vi) let F be substituted for its value in (ix) ; 

Then A = -5-f-^) W X«i+" (x) 

l + n\Kv ' 

luil u is a quantity not depending on H, the total depth of concrete, but on the 

depth of concrete capable of resisting tension — determined by the extent the material 



\I\Vo 7 




FIG 3 



is weakened by a crack or similar loss of cohesion, indicated in Fig. 3 and defined there 
by V — i'o. 

Then 11 = V — v () (xi) 

Substituting this value of u in (x) and reducing — 

Then 



l + n\I</ \vo I 



(8) 



The forces in tension — A s — in the reinforcement, due to the extension v and the 
sectional area a s of the metal : — 

A s =a s f (xii) 

In (xii) either a s or f s may be supposed known. 

In this instance, let a s , the sectional area of the reinforcement be known. Accord- 
ing to Fig. 3, the metal has extended an amount y, due to flexure of the beam, and from 
geometrical considerations the following ratio must fold — the reinforcement being 
supposed to run normal to the vertical section cn : — 

v:v. :<y,w„ (xiii) 

whence v = — ' ( x [ v ) 



3<3 



ALFRED FY SON. [CONCRETE; 

From (5) it is found that v = ^~. 

Equating these two values of ??, 

then fs— . (xv) 

v 
Substituting this value of f a in (xii) it is found that — 

, _a s E s <T T v .. 

•is- , <XVl) 

Or, as v=D—v , it will be found convenient to express (xvi) thus — 

As=a s Es<r T (—-l) (9) 

To determine the position of the plane of the neutral axis through the point O, 

Fig- 3- 

Collecting the terms on the right-hand sides of equations (7), (8), and (9) and 

equating them so as to conform with those in (6), the position of the point O may be 

found by solving the following equation for v '■ — 

BF„v„_ B f<M» /F W + " , „ (D \ . ... 

r lr-J x i\A --11 +a s E s <T T [—-l) (xvn) 

As the stress F and its corresponding strain <r T are both known, it may be con- 
venient to employ a coefficient of elasticity for the concrete in compression for such 
strictly defined stress and strain and introduce it into the equations. 

Thus let E c represent such coefficient of elasticity. 

Then E C = F ", and therefore * T = — (10) 

o"t- E c 

In (xvii) for <r T substitute its value in (10) and reduce; then — 

This equation (11) cannot always be solved algebraically, but if numerical values 
are substituted for their corresponding symbols, then v , which defines the position of 
the neutral axis, can be determined to any required degree of approximation by sonic- 
known method for such purpose. 

The position of the plane of the neutral axis through O, Fig. 3, having been found, 
the moments of all the forces about that axis which are acting at the section aa () can 
now be determined. 

Let M M and M s represent the moments about the neutral axis respectively of 
the resisting forces of compression in the concrete, of tension in the concrete, and of 
tension in the reinforcement, and let Mr, the sum of all those moments, represent the 
total internal resistance at the section, thus — 

M R = Mo+M+M s (12) 

The moment of resistance of each set of forces may be determined by taking the 
product of its value, as previously found, and the distance of its centre of resistance from 
the neutral axis. 

For M, , the moment of resistance of the concrete in compression. 



r y o~ v o 
if f o y o Sy 



M =Bl f o y o sy lxviii) 

" y =o 
Proceeding in a manner similar to that shown for finding .1,,. 

v'" /•.<-"-" 2H m)V» 

O " o o 

BF v 2 
Making y = v c . Then M„ = — (13) 

2 + ni 

3'4 



r&^J>%E£iNc£9 REINFORCED CONCRETE BEAMS. 

F>>r M, Hi'- moment of resistance of the concrete in tension. 

M = B//ySy (xx) 



Proceeding in a manner similar to that shown for finding A 

BFy 2+n 
(2+n)u n 



„ BF F" BFy 2+ " 

M= u»J- Y " ySy "(?. + „),,» 



Making y = u. Then M= (xxiii 

2 + n 

For reasons already given with respect to the value of /*", let the terms on the right- 
hand .side of equation (ix) be substituted for that symbol in (xxii). 

Then m=-^-(-£ ) X M (xxiii) 

2+n\Kv / 

F [ ) 

But u = V— v and o> = — °. - By equations (xi) and (10) 
E c ( ) 

Introducing those terms into (xxiii) and reducing, it is found that — 

Z + n\KE c ) o\ Vo ) 
For M s , the moment of resistance of tlie reinforcement in tension. 

M s = A s v (xxiv) 

Substituting for ,4 S in (xxiv) its value as given in (xvi) and remembering that 
v=D-v . yis = asE s <r T (D-v„) 3 (xxv) 

Vo 

Substituting for o> its value, as previously found, and reducing. 



Then Ms = a s EsF„v n (D_ [15) 

E c 



a- > r 



For M R the total moment of resistance at the section. 

Collecting the terms on the right-hand sides of equations (13), (14), and (15) and 
equating them so as to conform with those in (12), then the total moment of resistance 
at the given section is found to be — ■ 

«.-flri \^*(£yx{V-l)""}+**g*(D-l)' (.6) 
(2 + w 2 + /i\A£ c / \v 1 ) E c U'o ' 

With respect to the value of the moment of resistance generally, it is, of course, under- 
stood that it must be at least equal to the bending moment. 

Other functions, the numerical equivalents of which will be required, are as 
follows, and they can be deduced from the equations set against them : — 

The extension of the concrete at the bottom of the beam \ T i rom (viii) 

The unit stress on the concrete in tension due to \ T F ,, (4) 

The extension of the reinforcement ,, (xiv) 

The unit stress on the reinforcement f s ,, (^) 

From the foregoing equations the moment of resistance of a reinforced concrete 
beam can be determined for any description of concrete or metal reinforcement employed, 
provided the respective relations between stress and strain are correctly obtained. 

The general principles on which those equations are based include the value of the 
concrete in tension; they are framed in conformity with the laws of elasticity as usually 
accepted, and the main conditions on which the theory of flexure are based accord with 
the teachings of eminent authorities on the subject. 

I^et it be assumed then that results derived from those equations may be considered 
- art all events for present purposes — as being close approximations to practical and 
theoretical accuracy. 

(To be continued.) 

C2 315 



BUILDING TRADES EXHIBITION. 

o= 



(CONCRETE! 




THE BUILDING 

TRADES 

EXHIBITION, 

OLYMPIA 



The Building Trades Exhibition 
•which took place at Olympia last 
month ivas highly instructive and 
interesting, and, although no remark- 
able changes have taken place in build- 
ing methods during the tivo years 
which have elapsed since the previous 
eihibition, a certain development can 
be observed in the details relating to 
fire-resisting construction. — ED. 



Tins exhibition presents a unique opportunity to all those interested in the building 
trade, both professional and practical, for studying numerous points in connection 
with design and construction, which possibly they have never met with in practice, and 
almost unconsciously they learn much which is useful, and at a later date, when dealing 
with a new problem, take advantage of some material or method that first attracted 
their attention at Olympia. 

There is much to be said for these exhibitions; for example, the advantages of any 
particular system can be so readily understood when explained by a competent 
person ; further, the architect and the specialist are brought in touch with one another 
in a manner which is only possible on such occasions, while the systematic records of the 
exhibits cannot fail to be interesting, as they indicate the progress of the science of 
building, which is a fascinating subject, even to those whose daily occupation does not 
compel them to deal with these matters. 

CEMENT. 

The value of this material in building work has become so great, owing to the 
extensive use of reinforced concrete, that it is impossible to lay too much stress on the 
importance of studying the methods and products of the largest producers of Portland 
cement in this country, and on the stand of the Associated Portland Cement Manu- 
facturers (1900) Ltd. (No. 120, row F) there was much of interest. The stand 
itself is worthy of special mention, it being of pleasing design and w<'ll proportioned, 
as will be seen on reference to the photographic view here shown. The interior was 
treated with old oak panelled walls and timbered ceilings with large oak 
beams dividing the latter into three bays, with an ingle nook containing the old- 
fashioned fireplace a1 one end. The effect of this treatment was very cosy, and 
caused one to linger for some time before passing out again into the noise 
and bustle of the exhibition.. The exhibits of the company were excellent and varied, 
then- being samples of their well-known brands of Portland cement, including J. B. 
White & Bros., Hilton, Anderson & Co., Francos' "Nine Elms," Knight, Hevan & 
Starge's "Pyramid," "Anchor," " Bur ham," "London Portland," " Gillingham," 
Gibbs' " Diamond," " Eddystone," " Tingey's," " Veotis," " Robins," and also their 
special " Ferrocrete " brand, which is recommended and highly suitable for all classes 
of reinforced concrete construction. 



ub 



r y, CONSTBUCTlONAl.l 

K y engineering —J 



BUILDING TRADES EXHIBITION. 



The oemenl is made by 
shown depicting the material 




Exterior View of Stand of The Associated Portland Cement Manufacturers (1900) Ltd. 



mosl thorough and up-to-date methods, and samples 
al the various stages of manufacture, \\ hili th< i 

of 
c ( m : n t 
ground t o 
various de- 
g r c ' e - 
f i n ei 
Many bri- 
quettes and 
cubes of 
v a r i (j u s 
ages a n d 
m i x I ures 
for testing 
p u r p o ses 
w e r i- 
shown, and 
p r a c t ical 
tests were 
carried out 
during the 
e x hibition 
by the aid 
of a com- 
plete test- 
ing appara- 
t u s which 
is in con- 
f ormit y 
with the requirements of the revised British Standard Specification. Of particular 
interest were the various apparata for determining whether aggregates require washing 
before use, for ascertaining the proportion of voids in aggregates, and for testing 
concrete to 
see if same 
is mixed in 
the speci- 
fied propor- 
tions. An- 
other inter- 
esting fea- 
t u r e was 
the hydrau- 
lic crushing 
in a c h i ne 
ii^ed for 
testing 
c u h e s of 
50 sq. cm. 
area, this 
reading up 
to 50 tons 
a n d being 
m 1 d e a t 
tlii c o m - 
pany's e n- 
g i n e ering 
shops from 
their o w n 
designs. 

Various 
samples of 




Interior View of Stand 01 the Associated Portt.and Cbme 



it Manufacti kers (1900) Ltd. 
3>7 



BUILDING TRADES EXHIBITION. 



[CONCRETE] 



other materials were also shown, such as aggregates of all descriptions, both suitable 
and unsuitable for concrete work, and Plaster of Paris, Kee ne's, Parian, and Roman 

cements. T h e i r 
practical handbook 
entitled " Everyday 
Uses of Portland 
Cement " (3rd ed.), 
which treats with 
the economical em- 
ployment of Port- 
land cement for all 
purposes, was also 
on sale on the 
stand, and, in fact, 
the exhibits covered 
all points connected 
with this material. 

Messrs. Mar- 
tin, Earle & Co., 
Ltd., e x h i b i t e d 
various samples of 
their products, in- 
cluding their well- 
k n o w n " Rhino- 
ceros " brand, 
which is guaranteed 
to comply with the 
revised British 
Standard Specifica- 
tion, and " Ferro- 
duric," which is 
specially manufac- 
tured for reinforced 
concrete work and 
has been largely used 
for this purpose. 




Stand of the Expanded Metal Co., Ltd. 

REINFORCED CONCRETE CONSTRUCTION 

not as numerous a 



The exhibits in this section were 
and this fact was undoubtedly due, 
in a certain measure, to so many 
firms being unable to prepare suitable 
structural exhibits in the short time 
available for preparation and th • 
absence of ample outdoor space for 
large exhibits. While several of the 
leading firms were in evidence, many 
others, however, did not exhibit. 

The Expanded Metal Co., Ltd. 
(No. 157, row G), exhibited examples 
of expanded steel sheet and bar rein- 
forcement for all classes of construc- 
tional work, the stand itself, which is 
illustrated in the photograph, being 
formed entirely with concrete reinforced 
with their materials. One of the great 
advantages of expanded metal is the 
ease with which it can be handled and 
applied, as it consists ol stamped metal 
sheets which are used in conjunction 
with simple hangers, and as reinforce- 
ment it can be applied to footings, 
3i8 



might be expected, 




Reinforcement of the Expai 

Mi 1 \i. Co., Ltd. 



r • I CON5TPI ICTIONA LI 
[C\ EjM(il>'KL.BlNG ^J 



BUILDING TRADES EXHIBITION. 



columns, flooring, wails, roofing, and in fad any member or structure, h also forms 
.hi excellent openwork fence for divisions or machiner) guards, et< . I nits!; 

i xpanded steel is a later type of expanded metal, which consists of a series 
rihs, or main tension members, which, in the process of expansion, are left 

tected by light cross ties, which act as spacing members. The usual 
of expanded metal used in reinforced construction are the 3-in. diamond m< sh in 
its various weights, and the rib mesh, in which the ribs are constant in cross se< tion, but 
are spaced at varying centres, thus giving a variable cross sectional area acco 
to the number of ribs in section per foot run. The lighter qualities of the diamond 
are largely used as a metal lathing for ceilings and all surfaces where a ke) has to t>< 
obtained for plaster, and for this purpose it is preferable to wooden laths. A great 
advantage of this material is the impossibility of the strands of reinforcement becoming 
displaced during concreting, as the whole of the reinforcement is in the form of a solid 
sheet of steel network. Examples of " Exmet " brickwork reinforcement wen- also 
shown by the same firm, this material being made in three strengths from 24 gauge, 
22 gauge, and 20 gauge best mild hoop steel in coils of practically any length. It is 
embedded in the mortar between the courses at varying intervals and materially 
strengthens the brickwork. The use of these materials has become very popular in 
modern construction, and the firm have innumerable examples for reference. 

The General Fireproofing Co. (No. 95, row E) exhibited examples showing the 
application of their " Trusset," " Self Sentering," and Herringbone lath which are 
used for partitions, floors, roofs, and ceilings respectively, and the nature of which is 
shown in the. illustrations. The stand itself consisted of concrete piers formed of 
•' Self Sentering," supporting, sloping, and flat roof, constructed partly of " Self 
Sentering " and partly of " Trusset," and concreted over. Sus- 
pended ceilings were also exhibited constructed partly in Herring- 
hone lath and partly in " Self Sentering," and a fence was shown 






m^ 





" Trusset." 



" Self Sentering." 
The General Fireproofing Co., Ltd. 



Herringbone Lath. 



constructed of "Trusset" without any temporary shuttering. Partitions formed with 
each of the three materials could be seen, and also two sections of floors constructed of 
" Self Sentering," one being of arched form and the other a flat slab. 

Messrs. Hotnan & Rodgers (No. 130, row FJ. — The exhibits of this firm included 
their well-known steel and hollow tile floor, which is constructed with hollow- 
tiles about iS in. long and triangular in section placed between steel joists of a specially 
light section, and these bricks have a special projecting lip on the underside which 
covers the flange of the steel joist and may afford some protection against lire, din 
key for the plaster is afforded by specially formed grooves on the bricks, thus avoiding 
any hacking. Concrete composed of broken brick or ballast and Portland cement is 
Idled in on the top of the tiles to the required thickness. An example of their 
patent ferro-concrete floor was also given, and this is constructed id' steel rods 
passing through the main girders to form a continuous tie, thus being a combine 
of reinforced concrete and steel frame construction. The patent reinforced concrete 
partition of this firm was also shown, this being made of coke breeze, sand, and Port- 
land cement concrete slabs about 2 ft. 6 in. by 1 ft. 3 in., cast with horizontal steel 
rods in the top and bottom of each slab. A hole for |th-in. vr^\ is left vertical in the 
"litre of the slab and the nxl is inserted at the time id' fixing, this projecting about 
half-w.iv through the groove of the slab above (the slabs being laid to break join,). 
then grouted in with cement. 

Messrs. Richard Johnson. Clapham <£ Morris, Ltd. (No. 173, row lit 
this stand were displayed this firm's well-known " Lattice" and " Keedon " - 

319 



BUILDING TRADES EXHIBITION. 



(CQNCBEXEJ 




Stand of Richard Johnson, Clapham & Morris 



of reinforced concrete construction, and their " Bricktor " system of reinforced brick- 
work This system of reinforced concrete work has the advantage ol being very 
economical while being simple and efficient, and the exhibit was a very good one, as 

will be Men by the 
photograph of this 
stand, where the 
arrangement of the 
bars, etc., can be 
clearly seen. Various 
samples of " steel 
wire lattice," as sup- 
plied for the con- 
struction of the floors 
in many well-known 
buildings, were also 
exhibited. The at- 
tention of visitors 
was specially directed 
to an improved type 
of lattice in which 
the wires where they 
cross are securely 
fixed together by a 
special form of link. 
20,000 yards of this 
material are at pre- 
sent being used in 
the construction of 
the new No. S Dock 
Transit sheds for the 
Manchester Ship Canal Co. The advantages of steel wire lattice for concrete floors 
are : the ease with which it can be handled and fixed, the continuity of the bond (the 
material being made up to 200-ft. 
lengths), and its low cost. The wire 
used in its construction is of special 
strength, thus allowing of a minimum 
depth of slab being adopted, and there- 
by saving space and dead weight of 
concrete. The system of reinforced 
brickwork was well displayed, and 
examples of walls built upon this prin- 
ciple were exhibited. To demonstrate 
the lateral strength imparted to brick- 
work by the insertion of this reinforce- 
ment, a heavily-loaded test wall in the 
form of a slab supported horizontally 
was erected on the stand. 

W. Kennedy (No. 45, row ('1. 
These exhibits, although not actual 
examples of reinforced concrete con- 
struction, dealt with the bending and 
cutting of bars fur this work, and the) 
an- worthy of special mention. The 
" Kennedy " bar benders, which are 
hand-power, portable machines for 
bending cold bars of various sections 
for reinforced concrete, were shown, 
these being of various types, according 
to the size of the bars 1,, he treal d, 
that lisii d as No. 2a being worm- 
geared lo bend up to 1 \ -i 11 . dia. bar 
shows a machine for the expeditious 




\V Kennedy's Machi 



, with direct lexer for Hi. 
cutting of round bars for 



,1 1 «>k Ci 1 1 ing Round B 

hi work. The illustration 
reinforced concrete work, 



320 



," j. fONSTI.U)C"I"l3NAl.) 

L'it.N'dlM-.UMNG ^J 



BUILDING TRADES EXHIBITION. 



and interchangeable blades ran be readily fitted 
tees, and other sections. The frame of the tool i 
Martin steel plate, and is guaranteed to be 
absolutely unbreakable, and the longesl rods 
ran be readily fed into the machine from the 
Iron! of the gap. The price of these machines 
is very reasonable, and the initial outlay is 
soon regained in the saving of time and labour 
that is ensured by their use. 

Messrs:. J. A. King & Co. (No. 112, 
row F). — This firm are the makers of the 
well-known ".Mack" partitions, and ex- 
amples of these partition blocks and pugging 
slabs were shown, together with the " King " 
pumice concrete fire-, sound-, and vermin- 
resisting partition slabs, 2 in. to 4 in. thick. 
Examples of reinforced concrete work were also 
exhibited, together with their special " Ferro 
Glass" construction, which is utilised for 
pavement and floor lights, roofs, partitions, 
etc. This system consists of specially-made 
lens,-,, which are temporarily supported on 
boarding, while steel rods are introduced in 
each joint, these rods being continuous and 
forming a lattice reinforcement, the whole 
being then filled in with a cement grout. 
The advantages claimed for this system are 
that the maximum amount of light is 
obtained with the maximum amount of 
strength, and the appearance is good, and 
exposed metalwork, which always becomes 
rusty in such positions, is avoided. 

Reinforced Metal. Lid. (Nos. 136 and 
137, row F). — This exhibit was particularly 
interesting, as it showed a new type of rein- 
forcement for columns, and, according to the 



for cropping squares 
i formed of a single 1m a\ - ■ mens- 





Anchored Spirals, End View. 
Reinforced Metal, Ltd. 



Anchored Spirals, Side View. 
Reinforced Metal, Ltd. 

reports and tests, it is a type 
which should be largely em- 
ployed. Various columns were 
shown, and some of these had 
been under a test load as great 
as 1,237 tons per square foot 
of reinforced area, while others 
were shown at various stages in 
the process of construction and 
some prepared ready for testing. 
It is claimed by the owner of 
the patent that these columns 
have more than double the 
strength obtainable from any 
other combination of steel and 
concrete in which the same 
weights of these materials are 
employed. The diagrams show 
the nature of the construction, 
with anchored spirals and a 
centra] steel core, and it is 
worthy of notice that the la" r 
is so designed as to be 
braced by the anchored spirals 
and the encasing concrete shaft 

sufficient to 1 irry the w I 
the structural load during 

321 



BUILDING TRADES EXHIBITION. 



[CONCRETE) 



struction. It is therefore unnecessary to wait for the hardening of the concrete before 
proceeding with the floors above, thus enabling buildings to be constructed very expe- 
ditiously. An extensive series of tests of columns of this type have been carried out by 
Professor Andrew Gray, LL.D., F.R.S., Professor of Natural Philosophy at the 

University of Glas- 

f^s gow, and in the re- 

rff [ port he says of this 

^^■/^^^ { method that it " pro- 

|^ 7qj) l\ vides a composite 

material having the 
remarkable and ex- 
tremel y valuable 
physical property 

Pthat its modulus of 
Jt elasticity under pro- 

gressive loading in- 
creases with the in- 
crease of compressive 
stress." Apart from 
its practical value, it 
is thus, on account of 
this remarkable and 
unique property, of 
great scientific inter- 
est. Other columns 
which were tested to 
destruction carried 
loads as great as 
1,430 tons per sq. ft. 
of reinforced area. 
Copies of Professor 
Gray's report and 
other particulars can 
be obtained on appli- 
cation to Reinforced 
Metal, Ltd., 175, 
West George Street, 
Glasgow. 

Siegwart, L td. 
(No. 154, row G). — 
The exhibits of this 
firm included a r - 
m o ured concrete 
pipes and poles, ami 
the illustration gives 

l^w^ I JL" K 2. j Si^^m utility of this com- 

pany's products. The 
pipes are made as 
small as 8 in. dia- 
meter and as large as 4 ft., and for special work the size could be increased up to S or 10 ft. 
diameter. The concrete and steel an- woven together with mathematical precision by 
machinery and the socket is doubly reinforced; while the whole of the pipe is lined witn 
a special asphalt, also applied by machinery. They are made in longer lengths than 
other concrete pipes, thereby reducing the number of joints and saving the cost of labour 
in laying and jointing. 

Spiral Bond Bar Co., Ltd. (No. 30a, row B). Examples showing the application 
of " 'I risec " spiral bond l>ars for reinforced concrete work of all kinds, which i- claimed 
to h>- a mo?* reliable and economical type of reinforcement to use, were exhibited b} 
this firm. 

The Trussed Concrete Steel Co., Ltd. (No. 154, row G). The stand of this 
firm was very attractive, being a pavilion well designed in the Greek style, where the 
322 




Siegwart's Armoured Concrete Pipes and Poles. 



TT, CONSTRUCTIONAL 

1A ENGINEERING — , 



BUILDING TRADES EXHIBITION 



Doric order was employed, and it was constructed entirely of Ilv Rib, which is o 
the Kahn products. This material is a steel lathing which is stiffened al i 
3'. in. by longitudinal ribs, |-in. projection, thus giving ;i stiffness which 
its use as centering as well as reinforcement, ami for walls, partitions, etc., elimi 
the use of studs. Interesting applications of its use were shown in floor slabs supported 
l.\ both Hat and curved My Rib, the various stages of wall construction where ii is 
with supports, suspended ceilings at 4-l't centres, as compared with the usual u in. r 
iS in., and centering for circular columns. Sample partition slabs wen also shown, 
and generally the stand was admirably and tastefully arranged. 

The Vibrocel Co., Ltd. (No. 144, row G). — This firm exhibited for the first 

time at Olympia, and their stand contained much that was of interest. It is claimed 
thai the Vibrocel method of vibrating concrete in .silu produces a perfect imbedding of 

the most complicated forms of reinforcement without risk of displacement, thus secur- 
ing perfect adhesion and grip. The concrete being rendered non-porous and damp- 
proof, the reinforcement — however delicate it may be — does not corrode. The examples 
shown included pneumatic vibrators for vibrating concrete in situ, a 5-ft. hexagonal cell 
of reinforced concrete with walls 2 in. thick filled with writer, a similar cell in various 
stages of construction, specimens o<f concrete base blocks, pillars, etc.. and fragments 
of 5-ft. cells burst with screw jacks to show that pillar and cell wall unite into one 
mass without any weakness at their junction. 



CONCRETE BUILDING BLOCKS AND 
MACHINERY. 







Baumgarten's Block-making 

Machine. 



R. Ii. Baumzarten (Rep. of the First Cottbus 
Cement Goods and Machine Works) (No. 128, row F). — 
Various machines were to be seen on this stand for 
making all kinds of concrete blocks and tiles. Sand and 
cement, with breeze or gravel, mixed in various propor- 
tions, are the materials used with all the machines, which 
included types for making concrete roofing tiles, concrete 
bricks, partition slabs, concrete blocks, and other 
materials. Demonstrations were given during the ex- 
hibition, and the wall of the stand was erected with 
concrete blocks, while the office partitions and floor were 
formed with products from the machines. The two 
illustrations show the nature of some of the machines 
exhibited. 

Messrs. Stothert & Pitt, Messrs. F. L. Smith 
& Co. (Nos. 3Q and 40, row C). — There were various types of concrete mixers, both 
hand and power, exhibited on this stand, including the " Victoria " concrete mixer, with 

charging hopper, and with loader and water 
tank, driven by electric motor, and the 
" Smith " mixer, with charging hopper and 
a similar type of machine on truck with 
loader, engine and boiler, with special heat- 
ing arrangement. Some of the mixers were 
shown in operation, and the simplicity of 
the various machines indicated to the visitors. 

The (U.K.) Wioget Concrete Machine 
Co., Ltd. (No. 193, row J). — The exhibits on 
this stand were numerous and Interesting, 

and included the well-known " Winget " 
concrete block-making machine. This 
machine was shown in operation making 
hollow and solid building blocks of a maximum size of 32 in. by 16 in. bv 9 in., of which 
size as many as 500 can be produced in a ten-hour day by one machine. The office 
on the stand was built with these blocks in order that an idea of the good appear- 
ance could be obtained by the visitor, and there need be no monotony in 
blocks, as there are no less than nine varying patterns of face availabl 
" Winget " machine can also !,<■ obtained with attachments which allow the production 

323 




U ingf.t "'Express" Mixer. 



BUILDING TRADES EXHIBITION. 



[CONCRETE] 




of partition slabs keyed all round and hollow blocks keyed at the ends, of which two 
are made in one operation. A smaller and less expensive block-making machine, known 
as the " Titan," was also exhibited, and this makes hollow or solid blocks 16 in. by 
9 in. by 9 in., with plain or patterned faces, with four possible variations of the latter. 
One of our illustrations shows the " Express " concrete mixer, which was also 
exhibited in operation. This is a power mixer, and mixes the concrete in any 
state from dry to sloppy, as desired; it is largely used for concrete block work and 
for reinforced concrete work, and it has the advantage that the operations of dry and 
wet mixing are constantly in sight. Other exhibits included a " Winget " hand-power 
mixer for concrete, and the " Lumsdan " wood trimmer, of which an illustration is 
given. This machine is easily manipulated and give- excellent results, and is indis- 
pensable to the pattern maker requiring speedy work. Among the small acoessi ries were 
shown various concrete laying tools and 
moulds for balusters and paving slabs. 

Ransome-verMehr Machinery Co., 
Ltd. (Nos. 218 and 219, row K and bay 
26, Gallery). — The exhibits of this firm 
included a variety of machines for mixing 
concrete and other purposes, examples of 
which are shown in the illustrations. The 
mixers included a No. mixer with direct 
coupled petrol engine and elevating hop- 
per, large numbers of these being in use at 
the present time. In addition to this and 
other power machines, a compact hand- 
mixer, with charging skip and automatic 
water tank, was exhibited. Another 
machine was the Ransome stone drver, 
which is utilised for drving stone for 
making tar macadam, and is so arranged 
that each batch can be thoroughly dried 
in three minutes, while the capacity is 50 cu. 

and the Ransome pile extractor were of interest, the former being in use at the 

present time on various contracts, which include 
the Rosyth Naval Base, the new Port of London 
Dock improvements, and the new Smith's Dock 
at South Bank. The cement tester, of which an 
illustration i- given, is designed to supplement 
the existing tests rather than displace them, 
and deals with the hardening qualities of the 
material. The Ransome continuous filter, which 
was shown in operation, was of particula; 
interest, the water being subjected to the moving 
sand in such a manner that it is thoroughly 
filtered, while the filter is simple and economi- 
cal, with very little maintenance. 

CONCRETE GRANITE. 

Messrs. A. C. W. Hobman & Co. (No. 

11, row B). — Various samples of rag-stone for 

tar paving and tar macadam, and paving 

samples which had seen many years' wear, were 

shown, together with examples of " Clifton " artificial stone, " Cliftonite " ornamental 

paving, and " Emerite " and leaded non-slippery treads for heavy wear. 

Messrs. Sharp, Jones <f Co. (No. 171, row II).- On this stand could be seen 
various rock concrete sewer tubes and manholes, the latter having the p 
" Aquatite " base, comprising benching, channelling, and sewer connections. There 
were also example- of in k 11 mi,i, road gullies and rock concrete roi ling tiles, the 
latter requiring no nails, while the double interlocking arrangement assi-ts in the 
rigiditv of tin- n of. 



Winget " Llmsden" Wood Trimmer. 
yds. per day. The example of steel piling 




Sai mgakten's Partition and Pipe- 
making Machine. 



3*4 



r >„ coNstbwctional' 

[t i. ENGINEERING — , 



BUILDING TRADES EXHIBITION. 

FIRE-RESISTING FLOORS. 

There were several examples of fire-resisting floor construction, and, ii ad 1! 
those already described under the heading of " Reinforced Concrete Construction," the 
following are worthy of notice: — 

Messrs. Horace W. Cullum & Co. (No. 224, row K). This system i 
structed with special hollow bricks which arc used in conjunction with single '.1 
reinforcement, and it can be formed with clear spans up to 30 ft. The advainl 
claimed are : its lightness, rapidity of construction, sound-resistance, and no expan 
The floor can be constructed to carry any load, and when the spans are greater than 
}o ft., steel girders are introduced to cut up the floor into panels. 

The Kleine Patent Fire-Resisting Flooring Syndicate, Ltd. (No. 119, row F).— 
The stand of this firm was entirely constructed on their system, which consists (> f rein- 
forced hollow blocks 
that can he used over 
wide spans. It is 
claimed that this 
method gives a light 
form of construction, 
while it i.s sound- 
proof, and it can be 
rapidly executed. 

The Siegwart 
F i r e proof Floor 
Co.. Ltd. (No. 1, 
row A). — This sys- 
tem of flooring con- 
s i s t s of specially 
moulded hollow rein- 
forced concrete 
beams, which do not 
require any center- 
ing, thus avoiding 
delay on the site of 
operations and doing 
away with a large 
amount of moisture 
which is necessarily 
introduced with con- 
crete that is depo- 
sited in a moist con- 
dition in the work. 
The beams are 
plac d side by side on the supporting walls or joists, and the joists are then grouted 
with cement mortar, after which the floor is ready for the finishing surface material. 
A portion of a constructed floor was shown on the stand, and also the application of the 
beams to sloping roof work, and one beam was cut to expose the method of reinforce- 
ment both for longitudinal stress and shear. The concrete employed for the beams is 
carefully proportioned and mixed, and the aggregate consists of fine granite. 
FIRE=RESISTING PARTITIONS. 
The Muribloc (Partition Slabs), Ltd. (No. 68, row D).— This firm gave a special 
demonstration of their weight-taking partition slabs, and their exhibit also included 
samples of their special slabs, such as Muribloc anthracite clinker and cement partition 
slabs and the Muribloc patent inter-dowel key plaster slabs, with rough and finished 
faces. In addition to these there were given examples of reinforced concrete lintels, 
concrete fixing bricks and pugging slabs. 

The "Shark-Grip" Tiling Co. (1910), Ltd. (No. 23, row C).— The exhibit of 
this firm referred to the finishing of partitions and wall surfaces, with regard to cleanli- 
ness and hygienic principles, and included examples of the " Shark Grip " (paten; 
backed) tiling, opal tiles, which are guaranteed for five years against facial cracking, 
crazing, frost, heat, and vibration, and various specimens of terrazzo and mosaic 
and tloorings. 

325 




Stand of Messrs. Ransome-verMehr Machinery Co., Ltd. 



BUILDING TRADES EXHIBITION. 



[CONCRETE 



There were many other exhibits of fire-resisting partitions, a great number of these 
being on the stands" of those firms dealt with in the other sections, and no further 
mention or description is needed here. 

FIRE-RESISTING DOORS. 

Messrs. Chubb 6c Son's Lock and Safe Co., Ltd. (No. 170, row H). — There were 
numerous examples of fireproof safes and 
doors on the stand of this well-known 
firm, but quite the most interesting was 
the new patent steel and concrete door, 
which is suitable for party wall openings 
and similar purposes. It is made of a 
solid slab (2 in. thick) of reinforced con- 
crete covered with steel plates, the latter 
being made to interlock in such a way 
that the interlocking pieces and the fasten- 
ing rods inside between the two plates 
form the reinforcing members of the con- 
crete filling. The concrete is put in from 
the open ends, which are then closed by 
end-plates provided with inturned and 
twisted pieces embedded in the concrete. 
This new type of construction is to be 
shortlv submitted to a severe test by fire, 
under the B.F.P.C. rules. It can be 
adapted for hinged or sliding doors, and 
for fire-resisting cupboards. 

Messrs. Fireproof Doors, Ltd. (No. 
18, row B). — This firm exhibited their 
" Dreadnought " fireproof doors, which 
are claimed to have withstood a greater 
test by fire under the B.F.P.C. standards 
than any other door. The test comprised 
an exposure to a temperature of 2,000 deg. 
Fahr. for four hours. These doors mav be 
treated with panels or mouldings to give 
any desired effect. The " Empire " fire- 
resisting doors were also shown, these 
being somewhat lighter but equally strong, 
and much used for lifts, staircases, etc., in 
place of ordinary fire-resisting hardwood 
doors. There were also examples of the 
" Dreadnought " cabinets displayed, these 
being employed for the safe keeping of 
papers, etc. 

ROOFING AND WATERPROOFING. 
Messrs. D. Anderson 6i Son, Ltd- 

(No. 133, row F). — The exhibits on this 
stand included many roofing and pre- 
serving materials, such as the " Rok " roofing, " Stonifiex " felts, " Zerolite " insu- 
lating papers, " Sanador " felt for sarking purposes, " Sideroleum " wood preservative, 
and " Siderosthexi " anti-corrosive paint. 

The British Ceresit Waterproofing Co., Ltd. (No. 210, row J).— -This exhibit 
took the form of a small model house built in Ceresit-cement-mortar, and a few slabs 
with glass cylinders attached containing water and Cerosit-cement buckets. The small 
model was made to revolve in water, and was washed over with water by means- of 
pipes attached to the building in order to show the waterproofing qualities of the 
material. 

Messrs. George M. Callender & Co., Ltd. (No. 04, row D).— A number of 
waterproofing specialities were exhibited al this stand, one of the most notable of these 
consisting of a reservoir rendered watertight with Gallender's sheetings, which are 
adapted for tanks, sub-basements, swimming-baths, and similar constructions. A 

326 




Cement Tester of Messrs. Ransome-yerMehr 
Machinery Co , Ltd. 



[Iliglgilgg BUILDING TRADES EXHIBITION. 

model was also shown as an illustration of the waterproofing qualities I " I' 
when applied to a brick surface, which was played upon by water jets as a pr 
illustration. Other specialities included their various damp courses, " Bitus 
for iron and steel work, " Bitubond," for pouring into cavity walls to render them 
temperature-proof, and their " Veribest " natural asphalt roofing. 

The Ironite Co., Ltd. (No. 214, row J). — The exhibit of this firm consi d of 
examples showing the various applications of " Ironite," which is a fine mineral p o\ 
thai is mixed with water and applied to concrete or brickwork to fill the voids and 
render the material impervious to moisture. 

Messrs. Kerner-Greenwaod & Co. (No. 33, row C). — On this stand the visitor 
could see models, etc., erected for the purpose of showing the waterproofing qualities 
of " Pudlo," which is used in the form of a white powder that is mixed with the 
cementing material. There was a model house built with ordinary brickwork ami 
rendered externally with Pudloed cement, upon which a constant stream of water was 
allowed to play, and also a model flat roof holding water, and other examples which 
put a severe test on the material without producing any effect as regards the percolation 
of water. It is claimed that this material has no detrimental effect on the cement with 
which it is mixed, and, in fact, it slightly increases both the tensile and crushing 
strength of the cement used. 

Messrs. F. McNeill & Co., Ltd. (No. 103, row E).— On this stand were shown 
various roofing felts and sheeting, including the various types of the " Lion Brand " 
and " Lakumen," and other materials for roof lining and sound deadening. 

The Ruberoid Co., Ltd. (No. 152, row G). — The exhibit of this firm consisted of 
a building whereon were displayed the various applications of " Ruberoid " roofing to 
flat and pitched roofs. This material has been largely employed during the twenty-ante 
years it has been on the market, and it is the onlv prepared, flexible coloured roofing 
that is manufactured. It can be applied to any kind of roof work. It is interesting to 
note that the composition of the material has not been altered in any way since \t was 
first manufactured in 1891, although the firm have never ceased their researches since 
the material was first invented. 

Messrs. Vulcanite, Ltd. (No 105, row E). — Various models illustrating the 
application of patent vulcanite roofing and " Rexilite " roofing were given on the stand 
of the firm, who also exhibited their Bitumen Bridge asphalt and Standard asphalt for 
cavity walls, together with many other specialities. 

STEEL PILING AND METAL DOORS. 

The British Steel Piling Co. 

(No. 7 Bay, Gallerv). — The exhibit 
of the firm included various types 
of steel piling, such as the 
" Universal " joist steel sheet piling 
and the " Simplex " piling. The 
former type consists of various 
Simplex" Piling. sections of rolled steel joists which 

The British Steel Piling Co. are connected with special shaped 

clutches, and the latter is formed with 
a special section with interlocking flanges. The firm also make a specialitv of [tile- 
driving equipment, and have carried out the piling work on many important contracts. 
Steel piling is being largely used for important work in the present day, as there is no 
waste in cutting, it is much stronger and more reliable than timber, and can be driven 
more cheaply. The sections can be used a large number of times, and when finished 
with as piling will always find a ready market as scrap. The Blaw collapsible steel 
centering is another speciality that was shown, and this is adopted for centering for 
sewers, culverts, conduits, etc. The general principle of the " Blaw " system is 
simply steel sheet held at the curvature, by means of angle irons, etc., and turn- 
buckles. These turnbuckles on being screwed tighter, must necessarilv gently reduce 
tin- span of the cross diameter when they are fixed, and as the centres as a whole (in 
ih' case of arch work) are supported on wedges, when the wedges are loosened it 
follows that the whole centre must come away from the finished work gently. This 
very good system to adopt, as it is simple, saves time and money, anil givi 

3 27 





BUILDING TRADES EXHIBITION. [CONCRETE] 

finish to the concrete than any timber centre. The firm have numerous examples where 
their systems have been employed, which are good evidence as to the efficiency of their 
products. 

The Art Metal Construction Co. (No. 104, row E) showed various steel 

furniture and fireproof construction, the photograph illustrated being that of a typical 

exhibit. The specimens were 
very varied, and included par- 
titions, screens, adjustable 
shelving, and steel fittings in 
general, and some " Dahls- 
trom " doors, which were 

0^ "^^^w ^r recently submitted for official 

i_ /H^"" ~ m ^ m ^ m ^^r under the B.F.P.C. 

rules and obtained the 25-hour 
Universal Joist Steel Sheet Piling. classification. 

The Delta Metal Co., 
Ltd. (No. 174, row H), are the largest manufacturers of extruded metals, and they 
exhibited specimens of almost every section imaginable. This company do not make 
finished articles, but only supply their semi-manufactured specialities to the trade. 

The Crittall Manufacturing Co., Ltd. (No. 161, row H), showed metal windows 
of even- description, and their exhibit took the form of a building specially erected 
for the purpose of showing the various types in position in the work. Examples of 
fire-resisting doors were also to be seen. 

ASBESTOS SLATE FOR TILING. 

There were many exhibits by firms supplying these materials, amongst them being 
The Asbestos Slate and Contract Co. ("So. S2 and 83, row E), whose exhibit con 
sisted of a bungalow ; Messrs. Bell's United Asbestos Co., Ltd. (No. 168, row H), who 
were the first to manufacture " Poilite " Asbestos Cement tiles and sheet in Great 
Britain under the first Patent Act to be revoked under the new Patent Act of 1907 ; 
The British UrmliteCo. (1908), Ltd (No. 108, row E), who exhibited a whole building 
specially designed to show the adaptability of " I'ralite " ; The Calmon Asbestos and 
Rubber Works, Ltd. (No. 29, row C), who showed their well-known Calmon Asbestos 
roofing tiles, wall and ceiling sheets; and Messrs. G. R. Speaker & Co. (Xo. 63, row 
D), whose exhibit consisted of a wood and steel framed building covered with their 
" Eternit " slates and lined throughout with Speaker's " Eternit " sheets. 

VARIOUS. 

Messrs. Cassell 6t Co. (No. 50, row D), the publishers of Building World. 
exhibited copies of this technical journal, together with various technical books, 
including their recently-published book, Cassell's Rei>iforced Concrete, which 
appears to be having a good sale. 

The Compendium Publishing Co. (No. 194, row J) were exhibiting their 
publications, The Engineers', Architects' and Contractors' Conipcndiums, and the 
( 'ompendium Registers. 

Hudson & Kearns, Ltd. (No. 135, row F) had an attractive stand where the 
visitor could inspect various specimens of art and general printing, and drawing and 
tracing materials. 

There were many more interesting objects, but lack of space prevents their being 
described or even mentioned, and the organisers are to be congratulated on the excel- 
lence of the exhibits. We feel that a written description can hardly do justice to the 
work shown, which reflects great credit on the various linns responsible for their 
arrangement. 

In conclusion we would add that, as on previous occasions, the organisers ga> e 
every opportunity to the various technical societies interested to make a careful studt 
of all there was to hi- learnl regarding building construction by issuing special invitations 
to the membership of these institutions, and among those societies who enjoyed the 
courtesy of the authorities were : — The Institution of Municipal Engineers, the Institute 

328 



E 



CONyrBIJCTlONAn 



F-NGliNK^KlNCt 



S| 



BUILDING TRADHS EXHIBITION. 



of Builders, the District Surveyors' Association, the Institute of Clay Workers, the; 
Royal Sanitary Institute, the Society of Architects, the Surveyors' foi 
Concrete Institute, and the Institution of Heating and Ventilating Engineers 




Typical Exhibit of the Art Metal Construction Co. 



329 



REINFORCED CONCRETE PROVISION WAREHOUSE. [CONCRETE] 




PROVISION WAREHOUSE IN 
REINFORCED CONCRETE. 



_ 



The -warehouse described belo'w contains many features of particular interest, and goes 
to shoii) that reinforced concrete is admirably adapted for buildings of this kind "where food 
has to be stored in large quantities and sometimes for considerable periods, — ED. 



There has recently been completed near the south end of Blackfriars Bridge, 
London, for Mr. J. Sainsburv, Provision Merchant, a building- which is certainly 
one of the largest reinforced concrete warehouses in London. 

Not only does the use of reinforced concrete for this important structure 
afford one more proof, if such were required, of its economy and suitability 
where heavy loads have to be carried, and where protection against fire is a 
sine qua non, but the idea which seems to be current in some quarters that 
reinforced concrete is not a material which lends itself to quick construction 
has also been completely refuted. Throughout the progress of the work it was 
noticeable that the other trades were keeping back the concrete work rather 
than vice versa. 

The building, which is adjacent to the large previously existing premises of 
Mr. Sainsburv, is situated in Bennett Street and Stamford Street, being only 
about ioo yds. from the south bank of the Thames. It consists of seven floors 
and the roof, the outside walls being of masonry and brickwork, and the whole 
of the internal framework, footings, columns, beams, floors, staircases, etc., of 
reinforced concrete. The retaining walls supporting the roadways and foot- 
paths in Stamford Street and Bennett Street are also of reinforced concrete, 
and are of a somewhat unusual design, which is described later. 

Owing to their proximitv to the river, considerable difficulty was experienced 
with the foundations, portions of which had to be carried below the level of the 
water in the gravel. At one spot the inrush of water was so great, and the 
consequent disturbance of the gravel and sand of which the foundations are 
formed so serious, that it was necessary to resort to piling, but as a general 
rule the footings, both of the piers carrying the walls and of the interior 
columns, were designed of reinforced concrete in such a way that the load upon 
the gravel below was not more than could safely be carried by ii with- 
out further assistance. Two heavy internal walls cross the building, and the 
footings for these were, of course, continuous slabs, the sections of which are 
seen in the longitudinal section in Fig. i. Hut, in addition to the two wall foot- 
ings, wherever possible two or more columns were carried on a single strip 
footing in the form of an inverted tee beam. The sections of these are shown 
towards the right-hand side of the longitudinal section just referred to. 

A considerable economy, both of space and material, is effected bv this 

33° 



r /r coNM-pwcrioNAL| REINFORCED CONCRETE PROVISION WAREHOUSE. 



type of design, which has the further advantage of tying the bottoms of the 
columns together and thus stiffening them. It will be noticed that the footings 
are not all at the same level, the variation being due to the varying nature of 
the material as well as the requirements of the building. 

The basement is 
approximately 187 ft. 
long by 75 ft. bioad, 
and is surrounded on the 
two sides next the streets 
by retaining walls of 
reinforced concrete. The 
design of these walls 
consists of a slab vary- 
ing in thickness from 
6 in. to 8 in., supported 
by a system of vertical 
beams 10 in. by 10 in., 
a which are supported at 
g the bottom by the floor 
'o of the basement, and at 
2 the top by horizontal 

w 

a. beams, some of which 

o 

z run into the main columns 
« of the building. These 
2 horizontal beams also 

w 

g support the slab carrying 

S the load of the pavement 

^ and street above, this 

g slab acting as a beam 

~ from column to column 

I to resist the horizontal 

thrust of the ground 

against the retaining 

wall. 

T h e intermediate 
beams which do not run 
directly on to the main 
columns of the building 
are supported vertically 
at their inner ends by a 
longitudinal beam run- 
ning parallel to the wall, 
and supported in turn by 
those of the cross beams 
which run on to the main columns. (See Figs. 1 and 4.) 

It may be mentioned that, owing to the heavy nature of the traffic in the 
neighbourhood, the requirements of the district surveyor were very heavy in the 
n 2 331 




REINFORCED CONCRETE PROVISION WAREHOUSE. [QQNCBET E] 

case of these retaining walls and the pavement and mad slabs supported by them, 
a load of no less than 10 cwt. per sq. ft. having to be carried by the floor below 
the pavement, while the retaining wall had to withstand a super load of the 
same amount in addition to the load of the ground itself. 

It was, of course, 
necessary, under the 
London County Council 
regulations, to asphalt 
the back of the retaining 
wall, and in order to 
facilitate this a some- 
what unusual method 
was adopted, which 
proved very satisfactory, 
and will probably be 
used more frequently in 
future. The method 
consisted of building a 
P thin 4^-in. brick wall in 
^ small portions against 
u the ground, and care- 
£ fully retimbering this 
| brickwork as soon as it 
5 was complete. lust 

z before the reinforced 
p concrete wall was placed 
2 in position the brickwork 
% was covered with 
^ asphalt, and the concrete 

7. 

£ then placed against it. 
% This method avoids the 
- waste of space and the 
difficulty and cost of re- 
filling without danger of 
subsidence, which always 
exist when sufficient 
space is left outside the 
retaining wall to place 
the asphalt directly on 
the back of the wall. 

The floor of the 
basenjent over the sub- 
basement presents no 
special details, but the 
ground floor over the 
basement contains three loading cartways leading in from Bennett Street, and 
at the same level as the street — i.e., 4 ft. below the level of the ground floor. 
These cartways are designed to carry the heaviest form of motor lorries. They 
33 2 




[fi ^ffSiff^ REINFORCED CONCRETE PROVISION WAREHOUSE. 



are supported 1>\ main beams iS in. by [8 in., each carrying three secondary 
beams 14 in. In 8 in. ; the slab between the secondary beams being - 5 in. thick 
and covered with 4-in. granite cubes to afford a foothold for horses. I he 
of the cartways run direel into the columns and themselves form secondary 
beams carrying the outside bays of the slat). (See Figs. 3 and 4.) 

The fust floor, being' unbroken throughout its area, may be taken as typical 
of all the upper floors. 

The live load is in all cases 4 cwt. per sq. ft., this exceptionally large 
figure being due, of course, to the heavy nature of the goods to be stored. 

The main beams run parallel to the length of the building, which is divided 
into three portions by two main division walls of brick running right across 
the building from top to bottom. Each division of the building contains three 
consecutive spans of main beams, the centre of which is the greatest, 22 ft., the 
small spans being 16 ft. and 12 ft. in the centre and outside division respectively. 
The long span main beams are 18 in. by 10 in. and contain two i^-in., four 
i]-in., and two f-in. bars. 

The secondarv beams are nearly all 14 in. by 7 in. and contain two f-in. , 
two f-in., and two |-in. bars. 

The slab is 45 in. thick, and is covered by a i-in. thickness of granolithic to 
form a finish. This granolithic was put on as nearly simultaneously with the 
slab as possible, so that it should be monolithic with it. 

At the back of the building — that is to say, on the side opposite Bennett 
Street — the last bay is broken up to a considerable extent to allow of lift wells, 



£" 



ajjP^gjP^illiPJf Egg^jggj IPPpip i*** 1 **-** 




iai?:^ 



Fig. 3. Cross-Section through Cartway. 

Provision Warehouse" in Reinforced 
contrete. 

These lift wells are enclosed by slabs of reinforced concrete 3 in. thick, 
reinforced by a network of light bars running both horizontally and vertically. 

The N.W. and S.E. corners of the building are occupied by the staircases, 
which are of reinforced concrete formed in situ, and do not present any very 
special features, although a considerable number of cranked beams occur in 
which the reinforcement is somewhat intricate. 
The roof is well shown by Fig. 7. 

333 



REINFORCED CONCRETE PROVISION WAREHOUSE. [CONCRETE 



The centre bay for the greater part of the length of the building is raised 
by light trusses of reinforced concrete, so as to admit of glass lights being 

inserted between the 
fiats at the two levels. 
Three trusses occur at 
1 1 -ft. centres, and are 
supported on main longi- 
tudinal beams, 27 in. 
deep, reinforced by two 
;-in., two f-in., and two 
i-in. bars, and a tie, 
9 in. by 6 in., occurs at 
each column. The 
secondary beams sup- 
porting the flat portions 
of the roof are 6 in. by 
5 in., with three f-in. 
and two f-in. bars. The 
slab is 3 in. thick. 

Portions of the build- 
ing are raised to another 
floor, forming a dining- 
room and chambers con- 
taining lift machinery, 
etc. There is also a 
reinforced concrete tank 
to hold 15,000 gallons. 

As might be ex- 
pected in a building of 
so many floors carrying 
such exceptionally heavy 
loads, the size of the 
columns required in the 
sub-basement, basement 
and ground and first 
floors was found to be 
excessive if only the 
ordinary percentage of 
steel was used. It was 
therefore decided to in- 
crease the amount of 
steel and thereby reduce' 
the size of the columns. 
In the largest column no 
less than twelve [f-in. 
bars were used. 

I ho junction of the column bars at the various floors was effected in 

3 3 + 




for™i™&rff ^ REINFORCEDCONCRETE PROVISION WAREHOUSE. 

the usual way by lapping the bars in all outside columns, or wherever the c »lumn 
could conceivably be subjected to bending stresses; bul in the interior columns, 
where there is no possibility of any bending, loose sleeves were used, by means 
of which the ends of the b;irs were joined, thus saving space and allowing more 
room for concrete. This point is of considerable importance where there- is a 
ma--s of steel running into a column horizontally from four directions, and 
where, at the same time, there may be as many as twelve vertical column bar- 
in a small space; but, of course, it is an extremely dangerous method if there is 
the least possibility of any bending- stresses occurring- in the columns, as some 




Fig. 5. View of Floor in course of construction. 
Provision Warehouse in Reinforced Concretk. 

of the bars might then be put into tension. The " sleeve " method gives 
practically no tensional strength. 

A test load of il times the working load was applied to three floors 
simultaneously, so as to test not only each floor, but the columns and founda- 
tions at the same time. This is a point which is too often ignored. 

It is interesting to note the extremely small deflection under load which 
is nearly always obtained with a well-designed reinforced concrete structure. 
In this case the maximum deflection of the main beams did not exceed i 5400 
of the span. 

The work was carried out by Messrs. \V. Johnson & Co., Ltd., Wands- 
worth Common, from designs prepared by the Indented Bar and Concr 

? 5 5 



REINFORCED CONCRETE PROVISION WAREHOUSE. [CONCRETE 




Fig. 6. Fourth Floor. 




3 3 6 



I-"in. 7. Interior View of Roof. 
Provision Warehoisk in Reinforced CONCRETE. 



f ^coN.-mMicTioNAiJ REINFORCED CONCRETE PROVISION W'AL'EIIOUSE. 
l£y~" 



■ ENC.1NKI ■'.RlNCi , 



Engineering Co., Ltd., Queen Anne's Chambers, Westminster, the \ 
being under the direct superintendence of the architect, Mr. A. Sykes, 
F.R.I. B. A., of Finsbury Pavement, London, K.C. 

The various photographs, excellent as they are, hardly convey suffi< 
the clean and light appearance of the building, which has been obtained by the 




Fig. 8. Basement Retaining Wal 
Provision Warehouse in Reinforced Concrete. 



use of reinforced concrete. In spite of the very heavy character of the loads to 
be carried in building's for such purposes as the storage of articles of food, it 
is hardly possible to lay too much stress on the value from a sanitary point of 
view of a clean reinforced concrete job such as this. 



33: 



EDWARD N. HINES. 



(CONCRETE) 




CONCRETE ROADS OF WAYNE 
COUNTY, U.S.A. 

By EDWARD N HIN'ES. 

In "view of the impending International Road Congress to te held in June next, ana 
regarding "which a note appears in another column of this issue, nve give beloiu a Paper 
read on the subject of concrete roads at the Ninth Convention of the National Asso- 
ciation of Cement Users, Philadelphia, Pa,— ED. 



It is a sad commentary on the conduct of an undertaking of any magnitude that 
individuals, municipalities, states or nations, all seem to find it necessary to do a 
certain amount of experimenting and dilly-dallying before accepting the conclusions 
and avoiding the failures of previous demonstrations. This is particularlv true of the 
various phases of the good roads movement. 

\\ ith four years' experience as a guide, it has been demonstrated in Wayne Countv 
(Mich.) that a well-built concrete road is a practical form of construction which merits 
and will receive a more ext« nsive adoption. Every test to which our work has been 
subjected serves only to emphasise its strong characteristics. The points considered, 
which might properly be termed a specification, are : Initial cost, ultimate cost (which 
includes maintenance), sanitation and freedom from dust, g< m d traction for all tvpes of 
vehicles, smoothness and ease of construction. 

The initial cost of a good concrete road is little, if anv, greater than that of a first- 
class bituminous macadam road. One of the greatest fallacies indulged in by com- 
munities starting to improve their highways is that cheapness in cost of original con- 
struction of roads means economy and that the highway official who can build the 
greatest area of roads at the least outlay per square yard is working for the community's 
best interest. 

THE PAVING DETERMINATOR. 

About a year ago, as a result of the rapid deterioration of new pavements, the City 
of Detroit conducted an inquiry into materials used and methods followed jn paving, 
and the Common Council of the city voted $600 for testing purposes to decide the 
merit or lack of merit of the various forms of built-up pavement. Boiler Inspector 
McCabe designed a very ingenious machine whereby all the conditions met with in 
street traffic could be reproduced as nearly as possible. 

The machine is made to revolve about a vertical shaft which carries, on a bearing. 
a head, which forms a bearing for the steel frame, at each end of which are jointed T 
castings. These T castings earn, - the shaft upon which solid cast iron wheels are 
mounted. The wheels have a 3-in. tyre and carry a load each of 1,350 lb. They are not 
supplied with springs or shock absorbers of any description. Each shaft also carries 
-1 v< ral plungers on which are mounted horse-shoes, each one of which strikes a 75-lb. 
blow. The wheels are moved across the pavement by a train of gears. The measure- 
ment from outside to outside is 19 ft. 8 in., the greatest wheel radius is 10 ft. 10 in., 
and the least radius of travel of the inside wheel is 8 ft. 7 in. It requires 333 revolutions 
about the circle to move the wheels across the pavemenl 2 ft., which is the limit of 
travel. The foundation of all pavements consists of 8 in. of concrete. The paving is 
laid en 2 in. of sand, which is packed by a hand pounder until firm and uniform. The 
concrete sample is 6 in. thick and laid on the foundation. In the first experiment 
sections of cedar block, granite block, creosote blink, and three or four varieties of 
brick and concrete wen- tried out. The Detroit Free Press reports as follows: — 

" In the firsl experiment with the machine, it was run at a comparatively high 

338 



r. ccNSTBuiTicwAiJ CONCRETE ROADS OE WAYNE COUNTY, U.S.A. 

51 eed to give it a severe test, and the pavement which stood up best under this pu 
ment was the concrete laid under the specifications of the Wayne County Road 
Commission. The wear on the surface was hardly perceptible, while the sam< wear 
on granite block and all brands of brick tried was as great as \\ in." 

MAINTENANCE. 

While not belittling the principle of maintaining a road after it is built and 
following it out in practice, it seems to me, with Wayne County's experience, that it 
would pay other communities to adopt a form of construction on which it is not 
necessary to expend from $800 to $1,300 a mile yearly to keep it in fairly usable 
condition. Our concrete roads are sanitary, as there is no detritus from the road 
itself; there are few cracks and joints to hold dirt and animal droppings, and tin re is 
no dust. The drier the weather, the less dirt on them, as vehicles do not track mud 
from unimproved cross-roads in dry weather. Our concrete roads have a gritty surface 
and are not slippery in any kind of weather, affording good traction for all types of 
vehicles. Horses find good footing on them and automobiles do not skid in wet 
weather. It is not necessary to build concrete roads with any great amount of crown, 
and the tendencv to drive in one track — so apparent on macadam roads in the forma- 
tion of ruts — is eliminated, as the driver of a vehicle can, sit comfortably in his seat 
t.o matter on what part of the road he may be driving; neither can a horse pick out the 
beaten track, as on a gravel or macadam road, but must be driven or he will zig-zag 
oxer the entire road. A crown of 5 in. to the foot disposes of the surface water and 
tends to distribute traffic over the entire area of the road. Another desirable feature 
of concrete roads is smoothness. 

CONSTRUCTION NOT DIFFICULT. 

With all the other good points in its favour, concrete can ba handled with 
comparative ease, and, providing the work is carried on under skilled supervision, it 
can be laid with a working force of relatively unskilled labour. It must be borne in 
mind, however, that the addition of a little cement to a quantity of stone and sand 
does not make concrete. There is no material which will respond so quickly to a little 
care, and if proper attention is given to the detail of mixing and curing it will well 
repay in quality and permanence. 

DRAINAGE AND FOUNDATION. 

Drainage and good foundation are necessary for any type of road, and on a concrete 
road the greater care there is taken in this respect the better will be the final result. 
c\ well-drained, well-compacted sub-grade will eliminate cracks to a very large extent. 
Our countv is flat, and, although some few sections are sandy, the subsoil is largely 
of a heavy, sticky clay, therefore not easily drained. 

One of the bad features alleged against concrete roads is the tendency to crack. 
Li order to overcome this tendency, we prepare our subgrade as carefully as conditions 
permit, making it flat and rolling it hard and firm. Owing to temperature changes 
and the absorption of water, concrete is constantly in motion, and the flat subgrade 
tends to overcome frictional resistance and thereby prevents longitudinal cracking. On 
the first concrete road built the subgrade was crowned to conform to the finished 
crown of the road, and what I term, for the want of a better name, an inverted curb 
was used. On this road and on the first concrete road built on Michigan Avenue, 
where practically the whole road is built on a fill, we have developed more cracks than 
on all subsequent construction. These cracks, however, are well taken care of at 1 
small expense, by the use of a hot, refined tar and sand. On our concrete roads it is 
tin repair of these cracks that has made up surface maintenance cost, and with a well- 
drained, well-rolled, firm subgrade cracks of all kinds arc reduced to a minimum and 
aa- not to be seriously considered. We build our roads in 25-ft. sections to provide for 
contraction and expansion, believing it wise to make our lateral cracks beforehand, 
so as to properly protect their edges from chipping and spading. A metal plate, which 
is a development of previous experiments, is being used. This plate is about r\ in. 
thii k and 3 in. wide, provided with shear members which tie it securelv to the concrete 
base and wearing surface. It is shaped to conform to the crown of the finished road, 
and two thicknesses of 3-ply asphalted felt (about -j in.) are inserted between the two 
plates at each joint. The use of these plates has practically overcome the wear at the 

339 



EDWARD N. HINES. 



[CONCRETE 



joints, which are the weakest points in the concrete road, besides securing a smooth, 
even, continuous finish. 

Wayne County is poor in good road material and everything has to be imported. 
The best results were secured from the use of washed gravel ranging in size from 
v in. to i j in. and washed sand from | in. down. Freedom from loam, clay, or other 
foreign matter is absolutely insisted upon. We believe in a rich mix, using i part 
of cement to 3 parts of stone, with just a little more than enough sand to fill the voids 
in the stone. Our roads are constructed with a minimum thickness of 7 in. After our 
subgrade is prepared we place side rails of lumber 2 in. by 7 in., protected on the top 
by a 2-in. angle iron. The concrete is laid right on the natural subsoil, which is well 
sprinkled just previous to placing the concrete to prevent the water in the concrete 
from being absorbed by capillary attraction. A wet mix is used that has been thoroughly 
mixed before being placed on the road. No tamping is necessary, although a couple of 
men are employed to work in it with shovels. It is not wise or desirable to have the 
mortar and fine aggregate worked to the top, as it is the stone which is to receive the 
wear. After the concrete is in place no workman is permitted in any way to disturb 
the finished surface by stepping on it or throwing anything on it. A plank trimmed to 
the curvature of the road and iron-bound on the edges to give the road its proper 
shape is used. Two men saw this plank back and forth over the concrete, resting on 
the side rails or from boards at the sides of the concrete over which this strike-off 
rides smoothly. It is handled with sufficient care to eliminate the necessity for any 
considerable floating by the follow-up men. These follow-up men, or floaters, work on 
a bridge which rests on the form boards or rails at the side of the road, so that there 
is never any contact with the concrete. The final " smoothing up " is done with 
wooden floats of home manufacture. When the concrete has become sufficiently firm 
to permit the removal of the side rails, the finishers, to prevent a sharp division line 
between the concrete and the gravel shoulders, pare off the outer edges which are 
formed next to the rails. 

Each day's work is finished up to an expansion joint, and not more than twenty 
minutes is permitted to elapse between batches laid in one dav. The work of the day is 
covered with canvas, and the next day the canvas is removed, and, to prevent the 
concrete from drying out too rapidly, it is covered to the depth of about 2 in. with any 
sand or loose soil that may be available. The concrete is sprinkled for eight davs and 
roads are not opened for traffic until at least two weeks after the last concrete is put in 
place. 

Our trunk roads are built 16 ft. wide of concrete, and our secondary roads are 
built 15 ft. with a minimum width of 24 ft. over all. We have also built concrete roads 
with the metal 18 ft., 12 ft., and 10 ft. wide. The shoulders are usually built of lime- 
stone or gravel in two layers of 3 in. each and rolled with a 10-ton roller. This work 
is not started until the adjacent concrete is at least three weeks old. 

All work is done locally under the day labour plan, and in parts of the busy season 
as many as 1,200 workmen are employed and from 900 to 1,000 cars of materials a 
month handled, and we build a mile of road, in the aggregate, every three davs. 
Machinery plays an important part in the work. Gasoline engines furnish the motive 
power. Concrete is mixed in a mechanical batch mixer, which travels under its own 
power, and from which a boom projects capable of being swung in a semi-circle. All 
work is specialised: one crew prepares the grade; another gets the materials on the 
grade, which is done with such nicety as usually to make it unnecessary to haul in 
extra sand or pebbles to make a properly proportioned batch ; another crew handles 
the concrete; another builds the shoulders, etc. 

System is the keynote of the whole organisation ; and when one considers that we 
are conducting a business enterprise spending $600,000 a year, with 1,000 to 1,200 men 
employed working simultaneously at points 40 miles apart; that we are handling close 
upon 1,000 cars of material a month, receiving daily reports, making up payrolls, tracing 
shipments, keeping crews supplied with materials, and handling a voluminous corre- 
spondence; that all these and other details of a big business are handled in the office by 
four employees, at an expense to the county of $6,225 a year; some idea may be had of 
the methods employed. 



34° 



I 



CONSTHUITIONA 



a 



A REINFORCED CONCRETE (IRANI) STAND 




~ 1 



S REINFORCED CONCRETE 
I GRAND STAND FOR THE 
PUBLIC SCHOOL ATHLETIC 
FIELD, BROOKLYN, 
NEW YORK. 



By HAROLD L. ALT. 

The folloiuing article om the erection of a reinforced grand stand ai Brooklyn, Neiu 
York, has many features or interest, and should claim the attention of those specially 
interested in structures of this kind. — ED. 



In America, where much of the construction is new and the territory capable 
of being" built over practically unlimited, we find many innovations along archi- 
tectural lines, and it is not surprising that, although concrete is perhaps the 
latest practically developed building material, it has already been adopted and 
utilised in many ways in an expeditious manner which in other countries 
(more conservative in practice) would be quite unlikely, and perhaps even im- 
possible to attain. It is a considerable novelty, however, even in American 
construction, to utilise reinforced concrete throughout in the building of grand 
stands, except in perhaps a few of most recent construction. Even in these 
structural steel is generally used as a framework, with either a concrete or 
a wood flooring supported on the steel skeleton. 

A notable exception to this prevailing custom, nevertheless, is presented 
in the reinforced concrete grand stand which is nearing completion in the 
Borough of Brooklyn, City of New York, U.S.A. 

This stand is being built by the New York Board of Education on its athletic 
field, for the school children, which is maintained at the above site. The 
structure itself is being erected from designs laid out by Mr. C. B. J. Snyder, 
Architect and School Superintendent, who has complete charge of all the school 
buildings and other construction work carried out under the auspices of the 
Board of Education in the entire city. As far as the design itself is concerned, 
aside from the reinforcing details, which will be taken up later, there are several 
unusual features incorporated. 

Probably the novelty of greatest interest and of the most radical nature 
consists of concaving the front of the stand in such a manner as to render the 
entire track visible to those in the front rows without making it necessary to rise 
during the approach or recession of the contestants moving along the track in 
front of the stand. The concaving of the face of this stand is made just 
sufficient to eliminate this objectionable feature, as the track can be sighted 
through the hollow of the curve which in a straight stand would be obstructed 
by the front railing. 

The second notable feature consists of the removal of the superfluous 
hanger-on to a point where he is at least out of the way, if not elimir) 
This is effected by depressing the standing room or area in front of the stand 
and along the side of the track a distance of some 4 ft. and 6 in. below t 

3+' 



HAROLD L. ALT. 



[CONCRETE] 



level of the track itself. This brings the heads and shoulders of those con- 
gregating along the edge of the track just a little above the track level, and 
permits of their assembling in this depressed area at any point in front of the 
grand stand without cutting off the view of the stand spectators except for 
about 18 in. above the ground, to which height the heads and shoulders project. 
This feature is graphically shown in Fig. i, which is a typical cross section of 
the stand. 

Careful thought is also demonstrated in the arrangement of the judges' 
stand, which places the judges on three steps of different heights, so that their 




Fig. 1. Typical Cross Section of Stand. 
Reinforced Concrete Grand Stand, Brooklyn, N Y. 

angle of vision rises vertically from the finish line, and not (as is usually the 
case) in a line parallel to the track. 

The athletic track itself is enclosed on both sides with concrete curbing, 
in which brass markers are located by surveyors for a finish line and proper 
starting points for distances of 120, 220, 440, and SSo yards and one mile. 

Below the stand the Space is utilised principally for tw o locker and dressing- 
rooms, a cheek-room, and two toilet-rooms having been arranged as shown in 

34 2 



^noinSSTno^J a reinforced concrete grand stand. 



the plan, Fig, 2, with the check-room in the centre and one dressing-room 
and toilet-room on either side. 

Fig. 5 shows the south half <>l the floor plan of the top of the 
(grand stand floor). A fronl elevation of the south half as the stand will 
appear when finished is shown in Fig. 3 and the rear elevation in Fig. 4. 

In regard to the concrete construction there were problems met with which 
are not to a great extent encountered in ordinary work. The compound cross- 
beam, shown in Fig. 6, which was originally designed as a simple beam with an 
overhung cantilever end, it was decided later to support on the overhang b) 
small iron posts This was not because the beam itself is not strong enough 
to carry any reasonably supposed load, but in a structure of this kind unforeseen 
contingencies must be provided for. 

The walls of the building (with the exception of those of the boiler and coal 
room), the partitions, piers, girders, floor, stairs and gallery front are all of 
reinforced concrete. The walls of the boiler and coal room, the retaining wall 
in front of the stand, and the concrete curbing around the track are of mono- 
lithic construction without reinforcing. The partition separating the connecting 
passage from the checking room is made up of panels of No. 8 wire, of 1^ in. 
mesh, which is set in |-in. channel iron frames and supported with wrought iron 
pipe posts with flanged caps and bases, secured to the floor with expansion bolts. 

The forms used in this work were built in general of ^-in. matched and 
planed material, with the stiffeners of 2 in. by 3 in., 3 in. by 4 in., 3 in. by 6 in., 
and 3 in. by 8 in. in size, being spaced respectively 16 in., 18 in., 20 in. and 24 in. 
on centres, this being determined by the various spans of slab and thickness of 
concrete supported. The forms were driven tightly together to prevent leakage, and 
braced and supported in a most careful manner to insure smooth faces and abso- 
lutely true lines to the work. It is easy to see that great stiffness was required in 
this part of the work, as the specifications limited the variation from the figured 
sizes given on the plans to not more than | in. These forms were maintained 
a proper distance apart by wooden spreaders, which were later replaced with 
2 in. by 2 in. concrete struts, of a length exactly equal to the thickness of the 
wall. These struts were placed as often as required and the concrete poured in 
around them, thus casting the struts into the wall permanently. 

The composition of the concrete used in the construction of the stand for 
all the piers, walls, and the retaining wall in front of the structure, together 
with the floor or roof slab, and the curbs about the running track, is composed 
of a mixture of one part Portland cement, two parts clean, sharp, medium coarse 
sand, and four parts of f-in. and f-in. stone. The f-in. stone is used for the 
vertical construction, and the f-in. in the grand stand floor. 

The cement used was tested as follows : — 

After 24 hours' exposure in air when mixed neat, it had to stand a tensile 
stress of 200 lb. per sq. in. without rupture; and after 24 hours in air and six 
days in water it was required to resist 500 lb. per sq. in. Further, it was 
required to show an increased strength at the end of 28 days over whatever the 
tensile strength developed at the end of the first six. Practically all the concrete 
used was mixed dry in a batch mixer until the dry materials were thoroughl) 
and evenly mixed (great attention being paid to this portion of the work), after 

343 



HAROLD L. ALT. 



(KgSCKETEl 







4+ 



f frcr^TBucrtoNAU A REINFORCED CONCRETE GRAND STAND. 

which water was added and the mixing continued again until th< bai 
of an absolutely uniform character and colour throughout, and until the m 
was evenly distributed through the mass of stone. 'This unset concreti was n 
allowed to stand, but was immediately deposited as soon as the mixing was 
completed, any excess that was left for a period of longer than two hours not 
being allowed lo he used or even retempered. 

In placing the concrete in the forms it was used at a consistency so that 
it would quake in the wheelbarrows hut not so thin as to allow the stones 
in settle to the bottom. In the heavy walls it was puddled into position with a 
puddling bar, but in the thin 4-in. walls it was settled into place with the assist- 
ance of hammering on either side of the forms while the mixture was being 
deposited. The concrete was handled mainly by means of inclined runways, up 
which it was wheeled in barrows, the incline of the stand making this means 
peculiarly suitable. In casting the high columns in the back a hoist was used 
(since these were poured first), and the concrete was raised by the bucketful with 
a rope run through a single sheave, which was attached to a cross piece tem- 
porarily suspended from the form work for the columns. 

After placing the concrete the top surfaces were protected from the sun 
with a covering and were amply sprayed, especially during the first 24 hours. 

The reinforcing was, in general, of rods, with the exception of the wire mesh 
used in the grand stand floor. This wire reinforcement is of 4-in. mesh, with 
No. i) longitudinal wires and Xo. 12 h-m. diagonal tension wires, being made 
by the American Steel and Wire Co. The reinforcing' rods were furnished bv 
the Corrugated Bar Co., of Buffalo, X.V. Fig. 6 shows the method of rein- 
forcement at the stairways. 

In the beginning of the work experiments were made with various compounds, 
with the idea of producing a smooth finished surface on the concrete and to pre- 
vent sticking. Among these might be mentioned crude oil, soap, oil paper, etc., 
all of which did much toward helping out the sticking part, but very little tow aid 
eliminating the lumber marks of the form boards. Finally the inside of all the 
forms was covered with galvanised sheet iron, and this method was followed 
throughout. After the foundations were poured, the piers were built up separately 
to the lower side of the cross girders, being allowed to stand thus for 24 hours 
before the curtain walls, girders, and the top of the grand stand were started. 
The girders were notched and halved together, and where the curtain walls, 
panels, etc., weie to be cast later, short iron rod dowel pins were used, which 
were thoroughly greased and cast into both sections of the concrete. Although 
the pouring - of the skeleton and the walls of each section, extending from the 
foundation to the underside of the girders, was stopped temporarilv during the 
night, no longer period of suspension was permitted; and even when thus stopped 
the concrete was brought up to and finished against a metal strip, so as to 
leave a sharp, even, and tine hair joint when the additional concrete was poured. 
Upon resuming work after a suspension of this kind the surface of the previous 
construction was roughened up, then thoroughly cleaned and wet down, after 
which it was flushed off with a cement mortar composed of one part of Portland 
cement and two parts sand, whereupon the work was immediately continued. 
1 he grand stand floor was built in panels reaching from girder to g 

E 3+5 



HAROLD L. ALT. 



(CONCRETE! 




V) 

ft 



a 

5 



S z 



3 a 

a m 

to ~ 

ei u 



( j. C0N5TCUCT10NAL 
[ft. fcNGJNEERINCi — , 



A REINFORCED CONCRETE GRAND STAND. 



and extending half-way across. The rods which were used as connection dowels 
here were also greased, and the panels were extended from the from of the stand 
to the rear and sideways from girder to girder until completion, withoul cea 
the work during this time. The back columns and pilasters were built separately 
and the panels between were Idled in later. The expansion joints, consisting of 
two vertical joints, formed the entire length of the stand, together with ten 
joints in the floor slab over the girders and spaced about 24 ft. apart. All of 
these joints were tilled with mineral wax and oakum. 

All necessary small holes required to be placed in the concrete were formed 




Fig. 6. Cross Section showing Construction and Reinforcement. 
Reinforced Concrete Grand Stand, Brooklvn, N.Y. 

with tapered wooden plugs, which were dipped in paraffin so as to make them 
impervious to water and to assist in their removal. The railing supports con- 
sist of round bar anchors threaded and provided with nuts and locknuts, which 
were cast in the concrete at the points required. The seats are supported on 
2 in. by i in. wrought iron brackets, which are clearly shown in structural 
position in the photographs, and the seals themselves are formed by wo 
strips laid along these brackets and fastened thereto. 

The brackets have the lower arm resting on a short cross piece of angle 
iron which takes the weight of the seat, while the upper end is extended through 

e 2 34 



HAROLD L. ALT. 

ilir riser of the step with ;i washer and ;i nut placed on the inside. Afler the 
placing - of these brackets .ill the holes were filled up with a t— .2 cemenl mortar 





nn\t ure, 

The top 

348 



during \\ 1 
dressing" ol 



Figs. 7 and 8. 
Reinforced Com 

lich <>]>< ration 
i he passage a 



Showing I-"mnt and Rear of Stand. 
11 ii Grand Stand, Brooklyn, N.Y. 



ihe surrounding suifaccs were kepi well wet. 
nil entire grand slant! floor, including the risers 



I 



CCWTBUCTJCNAL1 



IN A 1.1 



A REINFORCED CONCRETE GRAND STAND. 



of the steps, is composed of i -in. finishing coal mixed from on< pari Portland 
cement, one pari sand, and one pari grit; iliis was put down .it one and 
same time with the rest of the floor and was floated to a true and sir 

finish. As soon as the forms could be pulled, and before tin- initial set had 
taken place, the entire outer surface was trowelled to a polish and all the 
corners and edges were rounded off. 

The outside of all the walls and piers was floated down with a wooden floal 
and the imperfections removed. The window frames were set in a good bed of 
roofers' cement. The outside walls were given a coat of while lead and Rock- 
away Beach seashore sand, and the inside walls and ceiling were rubbed down 
with a wire brush ready for painting. 

The pavements laid in the area in Iront ol the grand stand are built up as 
follows : — hirst a 7-in. bed ol clean steam cinders was put down, over which was 




Fi;4. 9. Plan of Step Reinforcement. 
Reinforced Concrete Grand Stand, Brooklyn, N.Y. 

spread 4 in. of broken stone concrete, and over the top of this a i-in. coat of 
dressing, which was carefully trowelled, then roughened with a toothed wheel 
and marked off into squares. The concrete used on this part of the work 
consisted of a mixture of one part Portland cement, two parts sand, and five 
parts of broken stone which will pass through a i^-in. ring; the top dressing 
is composed of a very rich mixture, namely, one part of Portland cement to one- 
part of sand. 

The running track is made up of the following: — 

A filling is first deposited (consisting of broken stone that will pass through 
a 2-in. screen), which is placed on top of a well-tamped bed e>f earth; the 
broken stone layer running from 3 in. to 6 in. thick and covered with 3 in. ol 
clean rolled steam cinders, and then 3 in. more of j-in. screen cinders mixed 
with clav in the proportion of two parts of cinders to three parts of clay. This 
entire mass was then rolled with a steam roller to a hard and even surface and 
well sprinkled. 



3 



THE CONCRETE INSTITUTE. 



[CONCRETE] 




It is our intention to publish the Papers and Discussions presented before Technical 
Societies on matters relating to Concrete and Reinforced Concrete in a concise form, and 
:n such a manner as to be easily available for reference purposes. 

The method 'we are adopting, of dividing the subjects into sections, is, ive believe, a 
netv departure. — ED. 



THE CONCRETE INSTITUTE. 

ECONOMY IN REINFORCED CONCRETE DESIGN. 

MR. JOHN A. DAVENPORT, M.Sc (Vict.), B.Eng. (Liverpool), 
AssDc.M.Inst.C.E., A.M.I.Mech.E., M.C.I. 

The following is an abstract of a Paper read at the 33rd Ordinary Genera] Meeting of 
the Institute. The various Tables comprised in the Paper are only given Jiere in 
summarised form. .1 short summary of the discussion is also given. 

PART I. 
Introduction. 

The question of economy in reinforced concrete design may be discussed with regard 

to : (1) The engineering structure; (2) the architectural structure. 

In order to design economical reinforced concrete structures manv factors have to 

be considered, some of which vary in all cases, but there are three fundamental points 

which influence all structures in the same way, and these are : (1) The effect of beam 

section on economy ; (2) the effect of percentage 
steel on economy; (3) the effect of layout or 
arrangement of beams, columns, etc., on 
economy. 

The total cost of any reinforced concrete 
structure, whether a single slab, column, a 
whole floor, or a complete frame, will be the 
sum of the total costs of the three items : Con- 
crete, steel, and centering, and these, in their 
turn, will depend upon the unit costs. Now 
these unit costs will vary for different parts of 
the one complex structure, but not for any 
single member ; so that while a mathematical 
expression for a single member is possible it 
would hi- impossible, owing to the very large 
number of variable quantities involved, to 
deduce a mathematical general expression for 
all classes of structure, simple and complex. 

The following unit costs are taken 
throughout : 

Concrete in beams and columns... 40-. per cu. yd. 
Concrete in slabs (per in. of 

depth) ... ... IS . per sup. yd. 

Centering t<> beams and columns .»>. per --up. yd. 

35° 





Table I. 




Cost of Beams 


10 ft. long, 


of Moment of 


Res 1st a no: = 


500,000 Ib.-in 


for Various 


Ratios of Jt^. 
b 


1 








Total Cost 


Per cent. 


d+i 


in Shillings 


Steel. 


~r 


of Beams 
10 ft. long. 


i-oS.S.* ... 


3 


37-54 


,, 


2i 


38-76 


,, 


2 


40-82 


,, 


I J 


4 V57 


,, 


I 


JS-48 


i-o D.S. ... 


3 


37-02 


,, 


-, 1 


! - ■ ; 1 


.. 


2 


40-45 


„ 


1^ 

1 


4 3*59 




3 


22-99 


1 beams 


2.', 


23-61 


with j-in. 


2 


2 (•''- 


-l.ili 


I .1 


26-43 




I 


J'i'Ji 


* S.S meai 


s single reinfi 


rcement. 


D.S. mea 


is double rein 


forcement. 



f y, CONSTRUCT} _ 

KiENGTNtXKlNC, 



5g*g ECOiVOA/y IN REINFORCED CONCRETE DESIGN. 



< Centering to sialic ... 

in column laterals (bent and fixed] 
Steel, main reinforcement (l>cni and fixed) 

Table II. 

Cost of Beams to ft. long, of Moments oj Resist- 
ance = i,ooo,ooo, 2,000,000, and 4,000,00" Ib.-in. 
d 1 
b 



for Vat ious Ratios of 



Sti 1 



K in Ib.-in. 



[•0 S.S. 



i-o D.S. 



T beams | 
with 4-in. -,' 
slabs 



T beams 

with 6-in. 

slabs 



T beams 
with 8-in. - 
-labs 



1,000,000 
1,000,000 
1,000,000 
1,000,000 
1,000,000 
2,000,000 
2,000,000 
2,000,000 
2,000,000 
2,000,000 
4,000,000 
4,000,000 
4,000,000 
4,000,000 
4,000,000 
1,000,000 
1,000,000 
1,000,000 
1,000,000 
1,000,000 
2,000,000 
2,000,000 
2,000,000 
2,000,000 
2,000,000 
4,000,000 
4,000,000 
4,000,000 
4,000,000 
4,000,000 

1,000,000 
1,000,000 
1,000,000 
1,000,000 
1,000,000 

2,000,000 
2.000,000 
2,000,000 
2,000,000 
2,000,000 

4,000,000 
4,000,000 
4,000,000 
4,000,000 
4,000,000 



d 1 
6 



3 

24 



1 4 



3 
2 4 

1} 

1 

3 

2i 
2 
i4 

1 
3 

*i 

2 
1 i 



3 
a* 

2 

ii 

1 

3 

2\ 

2 

i4 



3 

2j 



3 

24 



i4 



3 

24 



i4 



Total t 1 isl 
in Shillings 
of Beams 

10 ft. long. 



56-39 
58-19 
61-58 
66-05 
73-58 
84-92 
88-30 

93-73 

101-06 

113-60 

128-76 

I34-30 

143-18 

t.54"76 

174-70 

55-64 

57-84 

61-30 

66-38 

74-85 

84-49 

88-io 

93-71 

101-99 

115-42 

128-56 

134-40 

143-44 

156-70 

178-00 

33-6i 
34-48 
36-16 
39-22 

44-41 

49-32 

51-41 
55-03 

58-79 
67-68 

74-35 
78-27 
83-17 
91-04 
97-76 



* This section (23 in. by 19 in.) has Dot the 
same ratio of -~ i , because any smaller depth 

with an 8-in. slab would have the neutral axis 
in the slab. It is therefore taken as the shal- 
lowest possible T-beam section, and not because 

d+x . 



1 6d ;, d . 

/'17 per ton. 
Z10 per !■ 

stresses used in call 



600 lb. per sq. in. 
16,000 lb. per sq. in. 

16,000 lb. per sq. in. 



reinforcement from o-6 to r6 and double rein 



The 

si/.'-, are : 

I lompressh e 31 ress in 

concrete (columns 
in 1 beams) 
Tensile stress in steel 
( lompressive si i< 

steel (maximum in 

columns) 

PART II. 

Tbe Economical Beam Section. 

To determine the economical beam 

section it will be necessary to consider 
various ratios of depth to breadth, and 
various percentages, both of single and 
double reinforcement. The effect of 
varying the ratio of depth to breadth is 
first dealt with for a fixed percentage 
tension reinforcement, and a definite 
moment of resistance. The effect of 
variation of percentage reinforcement 
and moment of resistance are then con- 
sidered, after having determined t In- 
most economical ratio of depth to 
breadth. The tension reinforcement is 
firstly taken as I'o per cent, for all 
plain sections, the doubly-reinforced 
beams having various percentages of 
compression steel, and the moment of 
resistance is 500,000 lbs. 

Notes on Table I. 
An inspection of Tables I. and II. 
reveals several important facts relating 
to the economy of beams, and tin se 
are : — 

1. For similar loadings, a correctly 
designed T-beam section is much more 
economical than any other. 

2. For similar loadings, doubly- 
reinforced plain beams, with the same 
area of steel top and bottom, are more 
economical than singly-reinforced plain 
beams when the ratio of total depth 
to breadth is 2 or more; but they arc 
less economical than singly-reinforced 
beams when the ratio of depth to 
breadth is less than 2. 

3. For all types of section a ratio 
of depth to breadth of 3 is more 
economical than any smaller ratio. 

Effect of Varying Percentage Reinforce- 
ment on Economy in Plain Beams. 

The cost of plain beams with 
various percentages of singh and 
double n-inforcrmvnt are calculated 
by the expressions already stated, 
given in Table III., for a menu 
resistance of 500,000 lb.-in. 
forcement from 0*5 to ; per cent., are 

35' 



THE CONCRETE INSTITUTE. 



[CONCRET E) 



The important conclusions revealed by the table are- 

i For plain beams the most economical single reinforcemenl percentaj 

I to I"2. 



fr 



Table III. 




Effect if Varying Percentage on Cost of 


Beam* 10 //. long ior B = 


|)00,000 I').-!)'.. 


, d+i 
and - =3. 






Total Cost 


Per cent. 


in Shillings 


Steel. k. 


of Beams 




10 ft. long. 


o-6 S.S. . 


— 


37-5i 


o-8 S.S. . 


— 


37-73 


i-o S.S. 


— 


37'54 


1-2 S.S. . 


— 


37-45 


1-4 S.S. . 


— 


37-79 


i-6 S.S. . 




— 


37-82 


0-5 D.S. . 




1 


38-66 






3 


38-81 


,, 




1 


38-78 


.. 




1 


39-10 


i-o D.S. . 




I 


37-02 


,, 


■ 


37-iS 


)! 


1 


37-32 


.. 


1 


37-39 


2-0 D.S. . 


I 


38-07 


») 


! 


38-24 




1 

2 


38-07 




1 


38-74 


3-0 D.S. '. 


1 


W7A 




3 
* 


40-22 


,, 


1 


40-58 


„ 


t 

- 1 


41-39 





Tabi e IV. 




Ratio of 


Total Load to Total Cost for 


Columns with 1 pe> 


cent. Main Steel and 


T. ifferent Hoo^ings. 






Size of 
C( »re. 


Diameter 

of 
H< 11 iping. 


/>'• 


Total Cost 


b in. 


P 




</ in. 






10 • 10 


i 3 g 


0-26 


0-889 


10 ■ 10 


_3_ 


0-36 


— 


10 X 10 


J 
i 


0-2& 


0-891 


IOX 10 


1 

4 


0-36 


0-917 


10 ■ 10 


J 
t 


0-46 


0-921 


to 10 


5 
IB 


O-20 


0-911 


10 • 10 


1 R 


0-36 


0-932 


ie 10 


ft 


0-46 


0-946 


10 > 10 


ft 


0-56 


o-957 


10 • 10 


ft 


o-6/i 


0-946 


IOX 10 


f 


o-zb 


0-921 


10 • 10 


3 


0-3'' 


0-954 


to 10 


3 

s 


0-46 


0-975 


1.1 10 


3 


0-56 


0-991 


IOX 10 


g 


o-6& 


0-985 


6x6 


_3_ 


0-26 


1-202 


6 6 


II 


0-36 


I-JS2 


6 6 


in 


0-46 


1-287 


6 '1 


i« 


0-56 


1-307 


6 6 


ft 


o-66 


I-.P5 


6 6 


i 


0-2/) 


[■285 


6 6 




0-36 


1-328 


., 6 


1 


0-46 


I- 35 8 


,, 6 


1 


0-56 




6 6 


1 


o-66 


[•392 



2. Fur plain beams the most econoniica] 
double reinforcement percentage is- 1, 

with equal tension and compression 

steel. 

Economy in Reinforced Concrete Beam 
Construction. 

(a) Reinforced concrete T-beafhs, correctly 
designed, with the total depth three times the 
breadth of web, are more economical than any 
other section, for all values of unit cost and 
loading. 

(b) For plain beams, reinforced in any way 
whatever, the most economical ratio of depth to 
breadth is 3, for all values of unit cost and 
loading. 

(c) For singly-reinforced plain beams, the 
most economical reinforcement percentage runs 
from 1 to 1 "2, for all values of unit cost and 
loading. 

id) For doubly-reinforced plain beams, the 
most economical reinforcement percentage is 1, 
with equal tension and compression steel, for all 
values of unit cost and loading. 

(c) Plain beams doublv-reinforced mav be 
more economical than .similar beams sinoh'- 
reinforced, the relative economies depending 
upon the values of unit cost and ratio of depth 
to breadth of section, but not to any appreciable 
extent upon the loading. 

The foregoing conclusions are quit ■ in- 
dependent of any economies effected bv adopt- 
ing uniform sections throughout a design. 

PART III. 

The Economical Column Section. 

Square columns onlv will be considered in 
this part because they are oftener used in re- 
inforced concrete frame construction than any 
other section. 

The relative values of cost per ton of load 
will be practically the same for percentages of 
main reinforcement other than 1, s,> that 
Table IV. shows that the effect of variations in 
Literal reinforcement is 

1. For a fixed diameter of lateral the 
greatest economy of space occurs when the 
laterals are closest. 

2. For a fixed sparing of laterals the 
greatest economy of space occurs when the 
diameter of lateral is largest. 

3. For a fixed diameter of lateral the 
greatest economy of cost occurs when the 
spacing is closest. 

4. For a fixed spacing of laterals the 
greatest economy of cost occurs when the 
diameter of lateral is least. 

5. For a fixed spacing and diameter of 
laterals, tin- cosl of the laterals is the same for 
all si/es of columns. 

The results of Tables IV. and V. may 
now be summarised as follows : — - 






35 2 



[I, CONSTUULTIONAA.1 



ECONOMY IN REINFORCED CONCRETE DESIGN. 



Table V. 

Effect of Varying Percentage. Longitudinal 
Reinforcement on Cost. 



Economy In Reinforced Concrete (Square) Column Construction. 

(/) For ordinary values of unit cost, square columns, helically reinforced, are 1 
economical of tost when the diameter of lateral is small, the pitch of lateral is <. . 
bteadth of core, and the percentage longitudinal >> t < -< ■ I is high. 

(g) Increased economy of cost will . 
from the use of longitudinal reinfon nient 
having a lower yield point than ordinarj mild 
steel, provided such material be cheaper than 
mild steel. 

(//) The greatest economy of spaee is ob- 
tained by using large diameter laterals, pitched 
at o - 2 the breadth of core, and a high per- 
centage of longitudinal reinforcement. 

PART IV. 

Economy in Slab, Beam, and Column 

Construction. 

A floor of breadth 20 ft. and length varying 
with the slab spans, as will be more clearly 
seen later, is taken. This is divided into ten 
bays, supported by nine beams 20 ft. long 
between the walls, and by the walls all round 
the outside edge. The beams are taken as sup- 
ported at three points by the addition of a row of 
columns running down the middle of the floor. 
Superloads of from | to 4 cwt., advancing by % cw.t., and slabs of from 1 in. to 8 in. 
total thickness, advancing by h in., are taken. The slabs are designed as continuous 
slabs, with the four different percentages o - 6, o"8, ro, V2 single reinforcement, as it is 
expected that the most economical percentage will be included in this range. 



Size of 

Core. 


I Hameter 
of 


/>'. 


Total C'ust 


h in. 


Hooping. 
d in. 




P 


10 X 10 


A 


0-26 


0-893 


10 X 10 


i» 


o-2b 


0-889 


10 X 10 


18 


o-2b 


0-873 


IOX 10 


A 


o-zb 


o-86i 


IOX 10 


IS 


o-2b 


0-851 


IOX 10 


A 


o-2b 


0-842 


xox 10 


IK 


o-2b 


0-834 


6x6 


A 


o-2b 


1-216 


6x6 


A 


o-2b 


1-202 


6x6 


IB 


o-2b 


1-139 


6x6 


A 


o-2b 


1-091 


6x6 


A 


o-2b 


1-052 


6X6 


IS 


o-2b 


1-018 



Table VI. 


Slab with o-6 per cent. 


Single Reinforcement 


and i-in. Cover. 


Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


1 


2-60 


1 V 


3-20 


2 


3-80 


,i 


4-39 


3 


4-99 


3i 


5'59 


4 


6-19 


4i 


6-79 


5 


7-39 


5i 


7-98 


6 


8-58 


61 


9-18 


7 


9-78 


7i 


10-38 


8 


10-98 



Table VII. 

Slab with o-8 per cent. 
Single Reinforcement 
and \-in. Cover. 



Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


1 


2-63 


il 


3-26 


2 


3-89 


2.V 


4-53 


3 


5-16 


3l 


5-79 


4 


6-42 


4i 


7-o5 


5 


7-68 


52 


8-31 


6 


8-94 


6* 


9-57 


7 


IO-2I 


n 


10-84 


8 


n-47 



Table VIII. 


Slab with 


i-o per cent. 


S ingle 


Reinforcement 


and \-in. Cover. 


Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


1 


2-66 


\\ 


3'33 


2 


3*99 


2), 


4-66 


3 


5'32 


3i 


5-98 


4 


6-65 


A\ 


7-.3I 


5 


7-98 


5i 


8-64 


6 


9-30 


64 


9.97 


7 


10-63 


7l 


11-30 


8 


11-96 



Table IX. 

Slab with 1-2 per cent. 

Single Reinforcement 
and i-in. Cover. 



Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


1 


2-70 


i', 


3-39 


2 


4-09 


,i 


4-79 


3 


5-48 


3 J 


6-i8 


4 




4* 


7-57 


5 


8-27 


si 


8-97 


6 


9-67 


64 


10-36 


7 


n-o6 


7\ 


11-76 


8 


12-45 



The cost of slabs alone is taken first, and then the combinations of slabs, beams, 
and columns are afterwards considered. 

Economy in Plain Reinforced Concrete Slabs. 
The costs Of plain slabs an- given in Tables VI., VII., VIII., and IX., correspond- 
ing to ()■(), o*8, ro, 1*2 per cent, single reinforcement. For every thickness of slab fr 
t in. to 8 in., advancing by £ in., the slab span is calculated for the superloads 1. ' 
2 i* 3> 3i, 4 cwt. per sq. ft., this figure being necessary to get the length of fl< 
then the area of floor. 

;•- 



THE CONCRETE INSTITUTE. 



[CONCRETE] 



Economy in Slab and Beam Construction. 

Here we have T4>eams of 20 ft. span, supporting slabs of various thicknesses and 
reinforced with various percentages of steel, the cost being worked out per super yard, 
under the head of beams and slab, and the total cost obtained by addition. It is not 



Table X. 

Cost per Sup. Yd. 
of Beam and Slab 
Floors to cany i cwt. 
per Sq. Ft. Super- 
load. Non-continu- 
ous T beams of 20 ft. 



Span and Slab with 


o-6 per cent. Single 


Reinforcement. 


Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


1 


8-7 


iA 


7-4 


2 


7-2. 


2 A 


7-4 


3 


7-7 


3i 


8-i 


4 


8-6 


4i 


9-1 


5 


9-6 


5i 


io-i 


6 


10-7 


6A 


u-3 


7 


11-8 


7\ 


12-4 


8 


13-0 



Table Xa. 



Cost per Sup. Yd. 
of Beam and Slab 
Floors to carry 2 cwt. 
her So. Ft. Super- 
load. Non-continu- 
ous T beams of 20 ft. 



Span and Slab with 


o-6 per cent. Single 


Reinforcement. 


Thick- 


Total 


iir..- , j 


Cost in 


Slab 


Shillings 


Ins. 


per sup. yd. 


1 


13-03 


iA 


I0-IQ 


2 


9-48 


2h 


9-25 


3 


9-29 


3i 


9-52 


4 


9-85 


4i 


10-27 


5 


io-68 


5* 


II-IQ 


6 


n-68 


6.1 


I2iq 


7 


12-72 


7i 


I3-25 


8 


13-78 



Table XI. 

Cost per Sup. \ d. 
of Beam and Slab 
Floors to carry 1 cwt. 
per Sq. Ft. Super- 
load. Von- continu- 
ous T beams of 20 ft. 
Span and Slab with 
o-8 per cent. Single 
Reinforcement. 



Thick- 


Total 


ness of 


Cost in 


Slab 


Shillings 


Ins. 


per sup. yd. 


1 


8-7 


i 1 , 


7'5 


2 


7-3 


2.! 


7'5 


3 


7-9 


3l 


8-3 


4 


8-8 


4 A 


9'3 


D 


9-9 


5 A 


10-4 



6 
61 

7" 
7h 



ii-o 
n-6 

12-2 
12-8 

*3-5 



Table XIa. 

Cost per Sup. Yd. 
of Beam and Slab 
Floors to carry 2 cwt. 
per Sq. Ft. Super- 
load. Non-continu- 
ous T beams of 20 ft. 
Span and Slab with 
o-8 per cent. Single 
Reinforcement. 



Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd 


1 


13-04 


1 J 


10-27 


2 


9-5o 


2 i 


9-32 


3 


9-4.5 


Si 


9-70 


4 


10-05 


\i 


10-50 


5 


10-97 


5i 


11-48 


6 


12-00 


nl 


12-55 


7 


13-12 


7\ 


I3-64 


8 


14-211 



Table XII. 

Cost per Sup. Yd. 
of Ileum and Slab 
Floors to carry 1 cwt. 
per Sq. Ft. Super- 
load. Non-continu- 
ous T beams of 20 ft. 
Span and Slab with 
i-o per cent. Single 
Reinforcement. 



Table XIII. 

Cost per Sup. Yd. 
of Beam and Slab 
Floors to carry 1 cwt. 
per Sq. Ft. Super- 
load. Non-continu- 
ous T beams of 20 ft. 
Span and Slab with 
i-2 per cent. Single 
Reinforcement. 



Thick- 


Total 


Thick- 


Total 


ness of 


Cost in 


ness of 


Cost in 


Slab. 


Shillings 


Slab. 


Shillings 


Ins. 


per sup. yd. 


Ins. 


per sup. yd. 


1 


8-7 


1 


8-6 


i 1 . 


7-5 


i.V 


7'5 


2 


7-4 


2 


7-4 


2i 


7-6 


2i 


7-7 


3 


8-o 


3 


8-i 


3i 


8-5 


3* 


8-6 


4 


o-o 


4 


9-2 


4i 


9-5 


4i 


9-8 


;> 


IO-2 


5 


10-4 


5l 


I0'7 


5* 


ii-i 


6 


n-4 


6 


1 1-7 


6A 


12-0 


6A 


12-4 


7 


12-6 


7 


13-0 


7\ 


I 3'3 


7\ 


13-7 


8 


13-9 


8 


14*4 



Table XIIa. 


Cost per Sup. Yd. 


of Beam and Slab 


Floors to carry 2 cwt. 


per Sq. Ft. Super- 


load. 


Non-continu- 


ous T beams of 20 //. 


Span 


ind Slab with 


i-o per cent. Sifigle 


Reinforcement. 


Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


1 


1 V02 


1 A 


.10-29 


2 


9-58 


2* 


9-39 


3 


<rVi 


3* 


9-85 


4 


10-26 


A I 


10-73 


;> 


11-24 


5 J 


n-77 


6 


12- }5 


<>.'. 


I2-.I2 


7 


I.V5I 


7\ 


r4-09 


8 


I4-7I 



Table XIIIa. 

Cost per Sup. Yd. 
of Beam and Slab 
Floors to carry 2 cwt. 
per Sq. Ft. Super- 
load. Non-continu- 
ous T beams of 20 ft. 
Span and Slab, with 
1-2 per cent. Single 
Reinforcement. 



Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. vd. 


1 


12--M 


iA 


10-27 


2 


9-60 


2| 


9-51 


3 


9-66 


3h 


IO-02 


4 


10-45 


4i 


10-96 


5 


11-50 


5 A 


12-07 


6 


I2-6> 


6A 


13-26 


7 


13-89 


7 -i 


M-54 


8 


1 ,V 1 7 



35 + 



l& 



CONM RUCTIONAU 
KNfilNKF.RlNCi — , 



ECONOMY IN REINFORCED CONCRETE DESIGN. 



proposed to deal with all i ho super Loads already given, bul to deal ' with 

i cwt., 2 cut., 3 cwt., and 4 cwt. per sq. ft. 



K.B. 

per Sup. Yd. 

Beam and Slab 
Floors to cany 3 cwt. 
per Sq. Ft. Super- 
load. Non-continu- 
ous I beams of 20 ft. 
Span and Slab with 
o-6 per cent. Single 
Reinforcement. 



Table XIb. 

Cost pet Sup. Yd. 

of Hen in and Slab 
Floors to carry i act. 
per Sq. Ft. Super- 
load. Non-continu- 
ous T beams of 20 ft. 
Span and Slab with 
o-8 per cent. Single 
Reinforcement. 



I \I-.II, XI I B. 

Cost per Sup. Yd. 
of Beam and Slab 
Floors to carry j 1 wt. 
per Sq. Ft. Super- 
load. Non-continu- 
ous T beams of 20 ft. 
Span and Slab with 
i*o per cent. Single 
Reinforcement. 



I able XIIIi . 

Cost pa Sh 
of Beam and 
Floors to can y 
per Sq. Ft. k 
load. Non-continu- 
ous T beams of 20 '/ 
Span (dh/ Slab with 

1-2 /'(T (t'l/. 

Reinforcement. 



Thick- Total 


Thick- 


Total 


Thick- 


Total 


Thick- 


Total 


1 j t - — 1 '1 Cost in 


ness of 


Cost in 


ness of 


Cost in 


ness 1 if 


Cost in 


Slab. Shillings 


Slab. 


Shillings 


Slab. 


Shillings 


Slab. 


Shillings 


In^. per sup. yd. 


Ins. 


per sup. yd. 


Ins. 


per sup. yd. 


Ins. 
1 


per sup. yd. 
16-8 


I I/-2 


1 


17-2 


1 


I7-I 


i\ 13-0 


1; 


13-0 


li 


12-9 


li 


12-9 


2 1 1 -5 


2" 


11-5 


2 


n-6 


2 


1 1 -6 


2'. 1 1 -o 


1 1 


II-O 


2l 


1 i-i 


^ 1 


11-2 


3" io-8 


3" 


10-9 


3 


II-O 


3" 


II-I 


3i i°'9 


3i 


II-O 


3s 


II-2 


3l 


H'3 


4" ii-i 


4 


n-3 


4 


I i-s 


4 


it-7 


4.I ir-4 


4* 


n-6 


4 I 


1 1 -8 


4i 


12-0 


5 ii-8 


5 


I2-I 


5 


12-3 


5 


12-5 


5| 12-2 


5i 


12-5 


51 


12-8 


5i 


I3-I 


6 12-6 


6 


I3-0 


6 


13-3 


6 


13-6 


61 i3-i 


6-i 


1 3'5 


H 


13-8 


64 


14-2 


7 13-6 


7" 


14-0 


7 


14-3 


7 


14-8 


~\ 14-4 


7* 


I4"5 


7\ 


14-9 


7\ 


15-3 


8 14-7 


8 


I5-I 


8 


15-6 


8 


16-0 


Table Xc. 


Table XIc. 


Table XIIc. 


Table XIIIc. 


Cost per Sup. Yd. 


Cost per Sup. Yd. 


Cost per Sup. Yd- 


Cost per Sup. Yd. 


of Beam and Slab 


of Beam and Slab 


of Beam and Slab 


of Beam and Slab 


Floors to carry 4 cwt. 


Floors to carry 4 cwt. 


Floors to carry 4 cwt. 


Floors to carry 4 cwt. 


per Sq. Ft. Super- 


per Sq. Ft. Super- 


per Sq. Ft. Super- 


per Sq. Ft. Super- 


load. Non-continu- 


load. Non-continu- 


load. Non-continu- 


load. Non-continu- 


ous T beams of 20 ft. 


ous T beams of 20 ft. 


ous T beams of 20 //. 


ous T beams of 20 ft. 


Span and Slab with 


Span and Slab with 


Span and Slab with 


Span and Slabs with 


o-6 per cent. Single 


o-8 per cent. Single 


1 per cent. Single 


1-2 per cent. Single 


Reinforcement. 


Reinforcement. 


Reinforcement. 


Reinforcement. 


Thick- Total 


Thick- 


Total 


Thick- 


Total 


Thick- 


Total 


ness of Cost in 


ness of 


Cost in 


ness of 


Cost in 


ness of 


Cost in 


Slab. Shillings 


Slab. 


Shillings 


Slab. 


Shillings 


Slab. 


Shillings 


Tn>. per sup. yd. 
1 212 


Ins. 


per sup. yd. 


Ins. 


per sup. yd. 


Ins. 


per sup. yd. 


1 


2I-0 


1 


20-8 


1 


20-8 


1! 15-6 


il 


1 ,V5 


i-i 


15-5 


i4 


15-4 


2 13-5 


2 


13-5 


2 


13-5 


2 


13-5 


2 \ 12-7 


2.1 


12-7 


2| 


I2'7 


2 1 


I2'8 


} 12-3 


3 


12-3 


3 


12-5 


3" 


12-6 


Si I2-I 


3i 


12-3 


3i 


12-4 


3^ 


I2'6 


4 12-2 


4 


12-4 


4 


12-6 


4 


12-8 


4-' 12-5 


4} 


12-7 


4i 


12-9 


4i 


i3-i 


5 12-8 


5 


13-0 


5 


13-3 


5 


13-5 


5i i3-i 


5i 


13-4 


5i 


13-7 


5 1 


I4'0 


6 13*5 


6 


13-8 


6 


14-1 


6 


I4'5 


64 14-" 


61 


14-3 


M 


14-6 


61 


I.VO 


"' M'4 


7 


14-8 


7" 


1 .VI 


7 


I5"5 


7.I 14-9 


71 


15-3 


71 


I.V7 


73 


11. -i 


8 15-3 


8 15-8 


8 


I()-2 


8 





THE CONCRETE INSTITUTE. 



iCQNCBEXB 



I h<- calculated results are given in 
XIII.. XIIIa, XIIIb, and XIIIc. 



Himmarised form in Tab 



X, Xa, Xh. X. 



to 



Table XIV. 

Cost of Slab. Ream, and 
Column Construction 
to carry i cui. per 
Sq. Ft. Superload. 
Non-continuous T 
beams of 10 ft. Span 
and Slab with o-6 per 
cent. Single Rein- 
forcement. 



Thick- 
ness of 
Slab. 

Ins. 


Total 

Cost in 

Shillings 

per sup. yd. 


i 


~-i 


il 


6-o 


2 


6-o 


2* 

3 


6-4 
6-8 


3i 

4 

4* 

5 


7-3 
7-8 
8-4 
8-o 


5i 

6 


94 

io-o 


64 


105 


7 


ii-i 


7i 

8 


n-7 

12-3 



Table XV. 

( 'osi of Slab, Beam, and 
Column Construction 
to carry i cui. per 
Sq. Ft. Superload. 
Son-continuous T 
beams of io ft. Span 
and Slab with o-8 per 
cent. Single Rein- 
forcement. 



Thick- Total 

ness of Cost in 

Slab. Shillings 

Ins. per sup. yd. 




7-i 
6-o 

6-1 

6-5 

7-o 

7-5 

8-i 

8-6 

9-2 

9-7 

103 

10-9 

"•5 

12-1 
12-8 



Table XVI. 

Cost of Slab. Beam, and 
Column Construction 
to carry i cui. per 
Sq. Ft. Superload. 
Non-continuous T 
beams of io ft. Span, 
and Slab with i per 
cent. Single Rein- 
foi cement. 



Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


i 


7-o 


ii 


6-o 


2 


6-2 


z\ 


6-6 


3 


7-1 


3 \ 


7-7 


A 


8-3 


4 \ 


8-8 


5 


9"4 


5i 


io-i 


6 


io-7 


6J 


n-3 


7 


1 1 -9 


7i 


12-6 


8 


13-2 



Table XVII. 

Cost of Slab. Beam, and 
Column Construction 
to carry i cut. per 
Sq. Ft. Superload. 

Non-continuous T 

beams of io ft. Span 
and Slab with i-2 per 
cent. Single Rein- 
forcement. 



Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


i 


7-o 


r| 


6-o 


2 


6-3 


2\ 


6-7 


3 


7-2 


-> 1 

J"2" 


7-8 


4 


8-5 


4* 


9-1 


5 


9 "7 


5i 


IO-4 


6 


n-0 


61 


ii"7 


7 


12-4 


71 


13-0 


8 


13-7 






Table XIVa. 

Cost of Slab, Beam, and 
Column Construction 
to carry 2 cui. per 
Sq. Ft. Superload. 
Non-continuous T 
beams of io ft. Span 
and Slab with o-6 per 
cent. Single Rein- 
forcement. 



Thick- Total 

ness of Cost in 

Slab. Shillings 

Ins. per sup. yd. 



i q-6o 

i' 7-4 S 

2 7-36 
2* 7-51 

3 7-82 
3-V , 8-21 

4 8-68 
4J 9-i8 

5 9-64 
>1 io-is 

6 10-65 
6\ 11-16 

7 11-70 

7-' 12-2^ 

S 12-83 



Table XYa. 

Cost of Slab, Beam, and 
Column Construction 
to carry 2 cui. per 
Sq. Ft. Superload. 
Non-continuous T 
beams of 10 ft. Span 
and Slab with o-8 per 
cent. Single Rein- 
forcement. 



Thick- 
ness of 

Slab. 

Ins. 




Table XYIa. 

Cost of Slab, Beam, and 
Column Construction 
to carry 2 cui. per 
Sq. Ft. Superload. 
Non-continuous T 
beams of 10 ft. Span 
and Slab with 1 per 
cent. Single Rein- 
forcement. 



Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


1 


9-48 


i£ 


7-48 


2 


7-46 


2i 


7-<><i 


3 


8-09 


3i 


8-55 


4 


9-08 


A I 


9-62 


5 


IO-22 


5 J 


10-76 


6 


II-30 


6i 


II-9I 


7 


I2-SI 


7\ 


I.3 - I5 


8 


1 (-79 



Table XVIIa. 

Cost of Slab, Beam, and 
Column Construction 
to carry 2 cwt. per 
Sq. Ft. Superload. 
N on- continuous T 
beams of 10 ft. Span 
and Slab with 1-2 per 
cent. Single' Rein- 
forcement. 



Thick- Total 

ness of Cost in 

Slab. Shillings 

Ins. per sup. yd. 






I 


9-50 


I* 


7 '5 2 


2 


7*5 J 


2| 


7-8i 


3 


8-2 4 


3* 


8-73 


4 




4i 




5 


10-40 


5 1 


u-ofi 


6 


1 i-i'j 


6| 


12-28 


7 


12-93 


7b 


1 )-59 


8 


14-24 






356 



r*cw.™cTigNAq ECONOMY IN REINFORCED CONCRETE DESIGN. 



If wo take these figures as a minimum for floors n ft. centre to c< 

column and [2-in. slab ami beam in the average, the number * > t cu. ft. per su] i 

tl(H>r will be 9x11 = 99, say too, and the cost per cu. ft. of building will then 

work out — 

1 j 6x12 
I' or 1 cut. per sq. it. superload= o 72 pennv. 



2 cwt. 

3 cwt. 

4 cwt. 



7-36x12 ™ 

= i =0 00 pennv. 

100 r 

8-6X12 

= 1 03 penny. 
100 

9/6x12 
= =1 15 penny. 



These figures, of course, do not include anything for wall beams, staircases, walls, 
or anything exterior to the ordinary floor construction. 



Table XIVb. 


Cost of Slab, Beam, and 


Column Construction 


to carry 3 cwt. per 


Sq. Ft. Superload. 


Non-continuous T 


beams of 10 ft. Span 


and Slab with o-6 per 


cent. Single Rein- 


■ r cement. 


Thick- Total 


ness nt 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


1 


n-6 


i 1 . 


9-1 


2 


8-6 


z\ 


8-6 


3 


8-8 


, 1 


9-1 


4 


9"5 


a\ 


9-9 


5 


10-4 


5'. 


io-8 


6 


n-3 


u\ 


117 


7 


12-3 


7 1 


12-8 


8 


13*4 



Table XVb. 

Cost of Slab, Beam, and 
Column Construction 
to carry 3 cwt. per 
Sq. Ft. Superload. 
A' on-continuous T 
beams of 10 ft. Span 
and Slab with o-8 per 
cent. Single Rein- 
forcement. 



Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


1 


n-6 


i£ 


9-1 


2 


8-6 


2.'. 


8-7 


3 


90 


3* 


92 


4 


9-7 


4i 


IO-2 


5 


io-6 


5i 


II-I 


6 


n-6 


6i 


I2T 


7 


12-7 


7h 


I3'3 


8 


1.3-8 



Table XVIb. 

Cost of Slab, Beam, and 
Column Construction 
to carry 3 cwt. per 
Sq. Ft. Superload. 
Non-continuous T 
beams of 10 ft. Span 
and Slab with 1 per 
cent. Single Rein- 
forcement. 



Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


1 


n-5 


ih 


91 


2 


8-7 


2i 


8-7 


3 


9-0 


3i 


9'4 


4 


9-9 


4l 


10-4 


5 


10-9 


5 A 


n-4 


6 


1 1 -9 


6i 


1 -'5 


7 


1 .V 1 


7h 


13-7 


8 


14-3 



Table X\TIb. 

Cost of Slab, Beam, and 
Column Construction 
to carry 3 cwt. per 
Sq. Ft. Superload. 
N on-continuous T 
beams 0/ 10 ft. Span 
and Slab with 1-2 per 
cent. Single Rein- 
forcement. 



Thick- 


Total 


ness of 


Cost in 


Slab. 


Shillings 


Ins. 


per sup. yd. 


1 


"•3 


i| 


9-1 


2 


8-7 


2\ 


8-8 


3 


9-1 


3i 


9-6 


4 


io-i 


4i 


io-6 


5 


II-2 


5i 


1 1 -8 


6 


123 


6i 


12-9 


7 


1 .V5 


7 1 


14-2 


8 


ii-S 



Economy in Reinforced Concrete Slab, Beam, and Column Construction. 

(f) A rational arrangement of slabs and beams supported by columns is more 

mical than slabs supported by beams only. 
(j) A low percentage slab reinforcement is more economical than a high percentage. 
(k) A thin slab is more economical than a thick slab. 

The writer suggests the thicknesses 3 in., 4 in., 5 in., ami o in. a- the minimum 
thicknesses, respectively, for the super loads, 1, 2, ;,, ami 4 cwt. per sq. ft. 

DISCUSSION. 
The discussion was opened by the reading of a letter from Mr. P. J. Waldram. 

The following is </// extract from the letter ; — 
■' In a material which is heavy lor its bulk, safety and economy are often synonymous. 
Where large spans or heavy stresses are involved, a sufficient factor of safety is often only 
made possible by the exercise of rigid economy in structural weight, t'n fortunately, the v 
of Mr. Davenport's results as 10 unit COStS, as they stand, 0bviouslj depend upon the Jf 
of the fundamental data and upon the method- of calculating the sections compared. 

357 



THE CONCRETE INSTITUTE. 



[CONCRETE) 



" With regard to the former, it would certainly appear that the prices quoted of 40s. per 
cub. yd. for concrete, and j£io per ton for beam and slab reinforcements are figures which 
are open to question. 

" The stresses stated obviously limit the tables to 1:2:4 concrete, thus leaving out of 
consideration one of the readiest and most efficient means of securing the maximum economy 
in heavily stressed beams and in columns, viz., by the use of richer and stronger concretes 
in compression. 

" The formula? used for calculating double reinforced beam sections are not given. 

" The conclusion drawn that double reinforcement is more economical than single is 
misleading. 

" When the conditions of size and stress are such as to demand more than the econonvc 
ratio of tensile reinforcement, the strength of the concrete is the criterion of the moment of 
resistance. To attempt, under such circumstances, to assist the concrete by additional tensile 
reinforcements is almost futile, as can be seen from any curve of unit moments of resistance 
for varying proportions of reinforcement. 

"The au'.hor also states that the most economical ratio of compressive to tensile reinforce- 
ment is 1 to 1. This depends upon circumstances." 



Table XIYc 


Table XVc. 




Table XYIc 




Table XYII< . 




Cost of Beam, Slab, and 


Cost of Slab, Beam, and 




Cost of Slab, Beam, and 




Cost of Slab. Beam, and 




Column Construction 


Column Construction 




Column Construction 




Column Construction 




to carry 4 cwt. per 


to carry 4 cwt. per 




to carry 4 cwt. per 




to carry 4 cwt. per 




Sq. Ft. Superload. 


Sq. Ft. Superload. 




Sq. Ft. Superload. 




Sq. Ft. Superload. 




Non-continuous T 


Non-continuous T 




Non-continuous T 




Non-continuous T 




beams of 10 ft. Span 


beams of 10 ft. Span 




beams of 10 //. Span 




beams of 10 //. Span 




and Slab with o-6 per 


and Slab with o-8 per 




and Slab with 1 per 




and Slab with 1-2 per 




cent. Single Rein- 


cent. Single Rein- 




cent. Single Rein- 




cent. Single Rein- 




forcement. 


forcement. 




forcement. 




forcement. 




Thick- Total 


Thick- 


Total 


Thick- 


Total 


Thick- 


Total 




ness of Cost in 


ness of 


Cost in 




ness of 


Cost in 




ness of 


Cost in 




Slab. Shillings 


Slab. 


Shillings 




Slab. 


Shillings 




Slab. 


Shillings 




Ins. per sup. yd. 


Ins. 


per sup. yd. 




Ins. 


per sup. yd. 




Ins. 


per sup. yd. 




1 13-5 


1 


13-5 


1 


13-3 


r 


IV2 


1 1 10-4 


I* 


10-5 




i'i 


10-3 




i4 


10-5 




2 o-8 


2 


9-8 




2 


9-9 




2 9-9 


2i 9-6 


2i 


9-7 




2j 


9-7 




24 


9-8 




3 9-7 


3 


9-8 




3 


9-9 




3 


io-o 




34 9-9 


32 


io-i 




34 


10-2 




3 2 


10-4 




4 10-3 


4 


io-5 




4 


10-7 




4 


ie-S 




44 io-6 


44 


10-9 




42 


n-o 




44 


1 1'3 




5 1 1 -o 


5 


u-3 




5 


ii'5 




5 


n-8 ■ 




5* n-4 


54 


n-8 




54 


I2-I 




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13-8 




74 


14*3 




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8 13-9 


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Protestor Adams, M.Iast.C.E. (Vice-President C.I.), stated that there seemed to be a 
little confusion regarding the relative economy of single and double reinforcement. In the 
course of the paper the author stated that double reinforcement is not necessarily less 
economical than single reinforcement. Then, further on, he stated that doubly reinforced 
plain beams with 1 per cent, tension and compression steel are more economical than singly 
reinforced plain beams. 

With regard to the statement, "Any smaller depth ratio of depth to breadth than 3 to I, 
would bring the neutral axis inside the slab and the beam would then no longer be a T-beam," 
he had always consi lered whether the neutral axis is within the flange or within the web it is 
still a T-beam. 

With reganl to the Statement that "The elimination of columns increases the cost of con- 
struction," he took this to mean the elimination of columns altogether, not taking th< 
where they are used with main beams. 

35*' 



f&ENoSSS»Nu59 ECONOMY IN REINFORCED CONCRETE DESIGN. 

Mr. E. hiander Btchells, F.Phys.Soc, M. Math. A., A.M l.Mech.E., M.C.I. , said thai 
paper had the one advantage in it thai it showed a fax mure scientifii wa 
economj than is frequentlj adopted by builders who arc verj anxious to gel a par iai 
m iIk face of rivals who have an equal chance of procuring same. In that ca • 
device is to increase the working stresses in an arbitrary manner and decrea nding 

moments in the same way. With regard to the author's remarks on the economy in rein 
concrete (square) column construction) the word "helical" is rather ambiguous. As used in 
the R.I.B.A. Report, the word "helical" is restricted entirely to lateral reinforcements in 
the form of a cylindrical screw, and not a form which is square on plane. The point is 
important, because if the author in his paper has taken the form factor for helical rein 
ments when he has had in mind lateral reinforcements which are square on plane, then the 
result of equations in that case will not he in accordance witli the R.T.B.A. Report. 

With regard to the author's suggestion as to slab thicknesses of 3 in., 4 in., 5 in., and 
6 in. as the minimum thicknesses respectively for the superloads, a word of warning is needfuj 
to those who may he building within the County of London, and that is that the load on the 
floor is not the only factor in determining its thickness. In many cases the Building Acts 
require fire-resisting construction, and half an inch or one inch of reinforced concrete is not 
considered fire-resisting. 

Mr. R. W. Vawdrey, B.A., Assoc. M.last.C.E. (Member of Council C.I.), said he thought 
that j£'io per ton for the main reinforcement (bent and fixed) was altogether inadequate. 
He went on to remark on the difficulty of confining considerations to bending moments 
only, and whilst it might be necessary to confine one's attention to bending moments for such 
a purpose as that of this paper, it is a fact that all these per cents, and general descriptions 
of methods are vitiated to a very great extent by the question of shear. In a great many 
cases it is that far more than the bending moment on the beam which really determines the 
design. As to the general principle that has been adopted by the author, he thought the idea 
of working out in such detail the actual costs under various conditions was an excellent one. 

Mr. Ewart S. Andrews, B.Sc. (Load.), M.C.I. , said he did not see why the author should 
have given values for double reinforcement below what is commonly called the economical 
percentage, '675, because it seemed almost obvious that it was unnecessary below those values. 
With regard to the T-beam formula, he thought it would have been rather more satisfactory 
and valuable, since most of the calculations have followed the R.I.B.A. figures, if they could 
have been followed without much additional work to those T-beams. 

Mr. M. Noel Ridley, Assoc M.last.C.E., M.C.I , said there were several things in the 
Tables he did not quite understand, and referring to> Table II. he said he did not quite see 
win the author put the width of the beam i3'q, taking the 1,000,000 lb. resistance for a metal 
of 5-78 sq. in. He thought in some cases the single reinforcement had been taken in the 
bottom instead of double. Of course, there it would be usually double, and the width of the 
beam would be about 8 in. instead of i3'g. 

Mr. E. C. Williams, B.Sc: T-beams, being the major part of a building in reinforced 
concrete, must of necessity be the most important part of this Paper. In Table II., on T-beams, 
4-in slab, with 1,000,000 lb. bending moment, after the cost of the beams 10 ft. long, comes 
the factor of concrete, which is here a varying factor. Now, a beam with a fixed bending 
moment over a span of, say, 10 ft., would of necessity have a fixed shear. If that shear is 
constant, and we usually take 60 lb. a sq. in. on the concrete, then the concrete area must be 
constant. This concrete area does not enter into the consideration, of course, and the question 
of cost depends entirely upon the ratio of side centering fox steel reinforcement, and there 
must be a factor of the bending moment. 

Then, again, as regards the slab, he had worked out the question of cost for the slab 
himself, and found that that slab would be cheaper provided the cost of the steel in the slab 
were equal to the cost of the concrete. The centering cannot come into the question of cost at 
all. As regards the slab, it is purely a question between the concrete and the steel, whereas 
in a T-beam it is a question between the side centering of the beam and the steel. 

MR. DAVENPORT'S REPLY. 

Mr. Davenport: In replying to Professor Adams regarding the elimination of columns, 
the author said he had taken two schemes. First of all a 20-ft. floor supported on non- 
continuous beams 20 ft. of span, and worked up the costs, thus getting so much per superficial 
yard for the various thicknesses per yard of superloads. Then he obtained the effect of 
reducing the spans of the beams by adding a row of columns, which gave the cost per - 
yard, and hence the statement that the elimination of columns, that is increasing the spans 
of beams, increases the cost. 



THE CONCRETE INSTITUTE. [CONCRETE] 

Regarding the point raised of the T-beara with a neutral axis in the slab. This would be 
a T-beain, with a very much thinner slab, and the same benefit would not be derived from thai 
as compared with the full depth of the slab acting in compression. The compression area is 
reduced, and of course the total compression, that is, the total push, due to the stress in that 
concrete is reduced also, and the moment of resistance is reduced unless it is increased by 
doing something else, either increasing the breadth or in some other way. The question of 
double and single reinforced beams was put forward. In one place it is stated that they arc 
more economical, and in another place that they may be more economical. For the cases 
considered they are more economical, but in the Paper these costs are taken for a special 
reason, not necessarily because they are the best costs, but they are simply costs which would 
enable anybody, if they wished, to get costs of construction to any other unit cost by simple 
proportion. 

Replying to Mr. Etchells's remarks as to the thickness of the slabs, and the question of 
fire-resistance, the author remarked that he had not considered the question of fire-resistance 
at all, as this came under the heading of Architectural Economy. 

Replying to Mr. Vawdrey's suggestion that ^"10 per ton for the steel was too low, the 
author remarked that this might be so, but it formed a good basis to work from. 

After replying to several other speaker:-' remarks in detail, the meeting was terminated. 



;6o 



g 



CON5TPUCTIONA L 
ENGIMEER1NG — , 



NEW HOOKS 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the leading books tvhtch have appeared during the last few months. 



"A Treatise on Cement Specifications.'' By 
Jerome Cochran. 

London : Constable & Co. 1913. 6/- net. 

Although this work bears an English 
publisher's name on the title-page, it is 
entirely American in object and scope. 
Tlic author admits that American specifi- 
cations go into less detail than thus, ul 
Europe, and it is not likely thai engineers 
in this country will learn much from the 
specifications here printed, although the 
compilation will no doubt prove of value 
to their American colleagues. 

Both natural and puzzolan (slag) cemenl 
arc u>ed in the United States, hut it is 
interesting to note that the employment of 
either is excluded in the construction of 
reinforced concrete work or of any struc- 
ture subjected to severe or frequently re- 
curring structures, for which purposes 
only Portland cement may be employed. 

The tests described are similar to those 
generally used, except that the boiling test 
with thin pats is prescribed for the detec- 
tion of unsoundness, the Le ("hatelier test 
not being mentioned. The requirements 
is to fineness are much less stringent than 
those of the British Standard Specification. 
The limit of magnesia is fixed at 4 per 
cent., and that of S0 3 at 1-75 per cent. 
There is a useful bibliography of American 
publications relating to the testing of 
cements, with a few European references. 

" Reinforced Concrete Doors." 

Red Book of the British Fire Prevention Committee 
Xo. 173, dealing with Fire Tests with 3 reinforced 
Concrete Doors, constructed for Experimental 
Purposes to the Design of Commandant Welsch. 
Chief Officer Ghent Fire Brigade. Published at the 
Offices of the Committee, 8 Waterloo Place. Pall 
Mall, S.W. Price 3/6. 

The doors tested and reported upon in 
this Red Book are of a non-proprietary 
character, and were designed in Belgium 
in the public interest by Chief Officer 
Welsch, who is the Chairman of the 
Belgian Government Technical Commit- 
tee mi Fire Protection. 

The doors under test comprised two 
-ingle doors to two openings, fitted as 
sliding doors, and one set of double sliding 
doors fitted to a third opening. 

In the prefatory note it is stated that 
•' although the idea of constructing doors 
of concrete is not new, yet the use of such 
loors has been quite exceptional." 

r- 




Ungle Door No. - (Firh Sidi 



NEW BOOKS. 



A study of ilif Reporl will show that the 
tests were highly interesting, and they 
went to prove that subject to the remedy- 
ing of some minor defects in construction 

reinforced concrete doors would be a 
valuable addition to our fire-resisting 
materials. 

The two single doors were tested for a 
period of z\ hours at a temperature gradu- 
ally increasing to i,8oo° F., but not ex- 
ceeding 2,ooo°, and the double doors were 
tested for a like period under similar con- 
ditions. In each instance water was 
applied at the conclusion of the test for 
two minutes. 

All the three doors tested had a dimen- 
sion of approximately 4 ft. by 7 ft. 

A full log showing the progress of the 
tests is given. The Report contains illus- 
trations of the construction of the doors, 
together with numerous photographic 
views of the doors before and after test. 

By the kind permission of the Com- 
mittee we are here reproducing a view of 
one of the single doors showing the fire 
side of Door Xo. 2 after the test, and after 
the door had been removed. 

All the dimensions, etc., in the Report 
are, as usual, accompanied by their metric 
equivalents. 

A German edition of the Report has 
been published by the Committee's Con- 
tinental publishers. 

"Staircases in Reinforced Concrete and 
Artificial Stone" " Eisenbetontreppen 
und Kunststeinstufen." By Karl 

Mattbies. 

Berlin : Verlag 
Price M.2.25. 



der Tonindustrie-Zeitung. 1913. 



The construction of staircases in con- 
crete or artificial stone is a very common 
proceeding, whilst complete, self-support- 
ing staircases of reinforced concrete have 



been introduced into many modern build- 
ings, but the statical computation and 
design of such structures arc complicated, 
and probably lew engineers an- familiar 
with them. For this reason the present 
work, which describes the usual forms of 
construction and deals in detail with the 
nature of the stresses and the methods of 
computation, will be found useful. It is 
important to note that the choice of a type 
is often governed by local building regula- 
tions relative to fire-proof staircases. 
.Methods of testing are also described, in- 
cluding a method involving the use of a 
small portable hydraulic press, by means 
of which a load may be applied to one or 
more steps at once, and which may be 
found useful in other cases where it is 
required to test beams and other structural 
members on the spot, without removal to 
a specially-equipped laboratory. 
The book is fully illustrated. 

" A Primer of Cement" (" Zementbrevier.") 
By Dr. Hans Kuhl. 

Berlin: Verlag der Tonindusirie-Zeitung. 1913. 
Price 30 Pf . 

This excellent little compendium, a 
pamphlet of only 70 small pages, contains 
a remarkably complete statement of the 
essential facts relating to cements, their 
manufacture, properties, and use. The 
different types of cement (Portland, 
natural, iron-Portland, slag, etc.) are de- 
scribed and defined, and the methods of 
testing and the standards to be attained 
are enumerated in detail. The last section 
deals with the methods of mixing mortar 
and concrete for various purposes, in- 
cluding reinforced concrete construction, 
and the best proportions and character of 
aggregate, etc., for each case. The in- 
formation given is both concise and 
accurate. 



362 



g 



OONSTKUCTJCNALI 

ENCIM.l IJINQ- 



>(ALl 



REINFORCED CONCRETE OFFICES. 



NEW WORKS IN CONCRETE 

AT HOME AND ABROAD. 

Under this heading reliable information ivill be presented of neiv nuorks in course o\ 
construction or completed, and the examples selected "will be from all parts of the ivorld. 
It is not the intention to describe these "works in detail, but rather to indicate their existence 
and illustrate their primary features, at the most explaining the idea which served as a basis 
for the design. — ED. 

NEW OFFICES FOR THE "LIVERPOOL DAILY POST." 

Some new premises have recently been erected and completed for the Liverpool Daily 
Post. The two great points which had to be taken into consideration in the erection 




View showing Building in course of construction. 
New Offices for the ''Liverpool Daily Post." 

of the building were economy of space and safely against fire, and it was found that 
both these problems were solved by the employment of reinforced concrete. 
The building is an extension to the existing offices. There are >i\ stoi 
tion to a basement, which houses the engines. The walls are carried from door to 

F * 565 



NEW WORKS IN CONCRETE. 



[CONCRETE) 



floor by a reinforced concrete frame, and the floors are designed for a super-load of 
3 cwt. per sq. ft., and they are 4 in. thick. The building is of lire-resisting construc- 
tion throughout. 

The details of the reinforced concrete work were designed in collaboration with 
the architect, Mr. Aubrey Thomas, by Messrs. L. G. Mouchel and Partners, Ltd., 




View showing nearly-completed Structure. 
New OhFicES for the " Liverpool Daily Post. 



Westminster, S.W. The contractors were Messrs. Edmund Nuttall Co., of Man- 
chester, and the builder Mr. John Williams, of Liverpool. 

REINFORCED CONCRETE QUAY FRONT AT WESTPORT, IRELAND. 

When the Westporl Harbour Commissioners some time ago decided to extend the 
Westporl Harbour Quay, they considered the use of reinforced concrete, masonry, and 
timber construction. 

3 6 4 



i 



CONSTfiUCT* 
ENGINEERING 



[ONAD 

sas3 



REINFORCED CONCRETE QUAY FRONT. 



After getting preliminary tenders it was decided to erecl a reinforced concrete 
structure, and designs and tenders were invited from ,-i few specialist linns. 

The design adopted was as shown in Figs, i and _•, and the work was carried out 
accordingly. 

The quay front, which is about 200 ft. long, consists of a row of main piles 
14 in. by 14 in. section and spaced 6 ft. centres. Behind the main piles close sheet 

piling is driven in order to retain the sand filling. 

The sheet piles arc 8 in. by 14 in. in section, and the pressure exacted on them by 

the filling is trans- 
mitted to the main 
piles by three rows of 
horizontal walings, 
12 in. by 12 in. in 
section, two placed 
close together just 
above low water 
level and one placed 
somewhat higher up. 
On top of the main 
and sheet piling a 
heavy horizontal 
beam is built, tieing 
all the piles together 
at their upper ends, 
and serving as a base 
for the upper wall or 
apron. 

This consists of 
a nearly vertical 
slab, supported by a 
coping beam at its 
upper edge and by 
buttresses spaced 
6 ft. centres, and 
placed just above the 
main piles. 

The front edge 
of the coping beam is 
protected by a heavy 
steel angle, fastened 
to the concrete by 
means of rag bolts 
w i t h countersunk 
heads. 

The whole front 
part of the structure 
is tied back to the 
anchor piles by 
means of 12 in. by 
12 in. tie beams, 
spaced 6 ft. centres, 
one to each main 
pile, and c a r r i e d 



COPI/V& L£V£t.. 




. _ 


1 


1 


1 1 








1 J 


1 


T 




1 1 1 ;' ! ;' 1 1 1 M il 11 1 1 1 > I 1 1 1 1 1 

LUj LluJ NiiJn ,LLuj ililh |l111^ [iil\ U-Li-U [ill 

{} w y U y 'y y u 



Fig. 1. Front Elevation. 




Fig. 2. Cross Section. 
Westport Quay Extension, Ireland. 






through an old rubble wall, behind which the anchor piles are driven. 

In some places, where a building comes up close to the old rubble wall, it was 
found necessary to drive the anchor piles in front of this wall, but the tie beams were 
in all cases run through the wall, and concreted into it. 

There is one anchor pile to each tie beam, and they am 12 in. by 12 in. in section-. 

After the reinforced concrete work bad been finished the space between the 
rubble wall and the new reinforced concrete front was filled with sand, and : 
dredging could then be proceeded with. 

f** 3 6 5 



NEW WORKS IN CONCRETE. 



(CONCRETE) 




2>«- C. I CAP 





Side View. Section AA. 

Details of Timber Fenders. 
Westport Quay Extension. Ireland. 



Section BB. 



Three heavy timber fender piles were also driven in front of the reinforced concrete 
piles, and were carried up to 5 ft. above quay level and braced to the reinforced 
concrete, so as to serve as mooring posts also, as shown in Fig. 3. 

The Engineer for the work was Mr. E. K. Dixon, M.I.C.E., County Surveyor for 
the County Mayo, and the reinforced concrete work was designed and carried out by 
Messrs. J. & W. Stewart, of Belfast, London and Dublin. 

REINFORCED CONCRETE 

POSTS AT GROVELANDS 

PARK. 

The accompanying illustration 
shows some patent reinforced 
concrete posts used for fencing 
round the lake in the pictur- 
esque new park at Grovelands, 
Palmers Green, which was 
opened to the public last 
month. The posts are of York 
stone chippings and Portland 
cement concrete, 5 ft. long 
and 5 in. square, and have a 
neat cap of ornamental design. 
They are placed 8 ft. 6 in. apart, but closer on sharp curves, and are reinforced with rib 
mesh expanded steel supplied by the Expanded Metal Co., Ltd., of London and West 
Hartlepool, bent into column form, and are very strong and durable. Eor situations 
near water, these posts are especially suitable, as they are impervious to rot or decay, 
and indeed become stronger with age. They carry a i\ by 1% square iron bar set angle- 
wise in the posts, and the fencing is pleasing in appearance. The posts never vegetate 
but retain the natural stone colour, and there is no necessity to paint them, so that thev 
are well adapted for park or roadside fencing. 

The fencing has been carried out by Messrs. Tidnam and Co., concrete specialists, 
of Wisbech, from the designs and superintendence of Mr. C. Griffin Lawson, 
A.M.I.C.E., the Engineer and 
Surveyor to the Southgate 
Urban District Council. 

CONCRETE IN EGYPT. 

The magnitude of many of the 
great works in Egypt — such 
as the Assuan Dam — in the 
construction of which concrete 
forms the main element, is, 
from repeated description, well 
known. 

Concrete, however, has 
other, if smaller, fields of 
utility in the land of the 
Pharaohs, one of these being 
that which the Egyptian Delta 
Light Railway Company, 
Ltd., finds for it. 

For a long time this Com- 
pany was confronted with the 

problem of erecting quarters for certain of its subordinate station officials (native 
Egyptians) at a cost which would enable a rent to be charged commensurate with the 
necessarily small salary drawn by those officials, and yet provide a reasonable rate of 
interesl on the capital outlay. Reinforced concrete afforded the only practicable solution, 
after extensive trials. 

The unit is one room and an enclosed courtyard for menials, with two rooms and 
a courtyard for assistanl station masters, and three rooms and a courtyard for station 

masters. Each room has an area of I by 5 m., a height in front of X m. and at the 
366 




Reinforced Concrete Posts. 
Grovelands Park, Palmers Green. 



r y T coNyreucTioNAEj 

1/ X E,NGJNK,EK1 NO — J 



REINFORCED CONCRETE IN EG 



rear 2*50 m. The single courtyard is 2*50 m. broad l>v 3 m. long, and th< •' mble court- 
yard 2*50 m. broad by 6*20 m. long, all inside measurements. 

The walls arc built of concrete, the method of construction being as follows : 
Timber moulds were first of all made according to drawings at a cost of £15. 
arc then placed on the ground at the site of the building longitudinally, so arranged as 
to conic into position when raised vertically. The insides an- coaled with oil and the 
reinforcing element consisting of discarded semaphore win- is laid in such a manner 
as t.i form a network, the ends extending some 2 ft. outside. The window and dooi 
for each unit is then put in place. The concrete mixture consists of — 

tt in. diameter Abou Zaabal gravel, 3^ parts. 

Fine sand, i\ parts. 

Gillingham Portland cement, 1 part. 
It is poured into the mould and subsequently kept moist by means of wet sacks, being 
left to set for seven days. The sides of the moulds are removed and the slabs, now- 




Double Unit Reinforced Concrete Hut. 
Staff Quarters, Egyptian Dei.ta Light Railways. 

set, are raised on end into position by means of a winch and shear-legs. The edges are 
joined by the passing of a f in. dia. iron rod vertically and looping the projecting ends 
of the reinforcing wire round it, subsequently giving the whole a covering coat of 
cement. 

The whole of the structure has a clean face and requires no touching up what- 
soever. The roof is of ordinary galvanised iron. 

The cost of constructing the single unit, one room and courtyard, in the manner 
described is ^7i2, the double unit like the one illustrated costs £25, and the treble 
unit ,£.'40. The annual rent is fixed at 10 per cent, of this, and is gladly paid by the 
stall, as no equally substantial habitation, and one so easily kept clean, can lie obtained 
locally for double the sum, and the amount is well within the means of even the lowest 
paid employed 






MEMORANDA. 



^CEETFJ 




Memoranda and Ne-ws Items are presented under this heading, -with occasional editorial 
comment. Authentic news ruill be "welcome. — ED. 



The Application of Reinforced Concrete to Rural Housing. — \n the course of 
an interesting paper on the subject of reinforced concrete generally, read before the 
Surveyors' Institution las* month, Mr. Percy J. YValdram spoke at some length as to 
the possibilities of using reinforced concrete to solve some of the difficulties of building 
cheap cottages in rural districts. He pointed out that the essential requirements of 
cottages and small houses in rural districts are (a) that they should be inexpensive, but 
efficient and durable ; (b) that the walls should not only be weather and damp proof, 
but form an insulation against changes of temperature; (c) that they should not dis- 
figure the landscape ; and (d) that they should be sufficiently substantial and fire- 
resisting to comply with reasonable or reasonably interpreted by-laws. 

The author stated that there could be little doubt that a cottage built of reinforced 
concrete in the form used for warehouses and office buildings would be extremely costly. 
But there were other ways in which the properties of cement concrete and the particular 
advantages of reinforced concrete could be enlisted. 

He pointed to the hollow concrete building blocks made by hand machines which 
any intelligent labourer could operate, and went on to show the different ways in which 
these blocks can be employed and finished off. 

He described various ways in which the reinforced concrete could be applied 
advantageously and economically, and how, bv adopting certain methods in wall 
construction, saving could be effected. The paper was followed by a discussion. 

New Wharf for Dundee in Reinforced Concrete. — The Dundee Harbour 
Trustees have decided to construct a new wharf of reinforced concrete. The wharf is 
to be 650 ft. long and 60 ft. wide. The total estimated cost, including necessary 
equipment, will be about ^120,000. 

The British Fire Prevention Committee's Testing Station.— The British Fire 
Prevention Committee's Testing Station, which has been recently remodelled and 
enlarged, is to be opened for its new session on Wednesday, May 7th, and an interest- 
ing series of fire tests, with both non-proprietarv and proprietary building materials, 
has been announced for the coming summer. 

On the opening day the tests are to be with fire-resisting glazing and with rein- 
forced concrete party-wall doors, and a large attendance from the various Government 
Departments concerned, who subscribe to the Committee, is expected. 

On the opening of the Testing Station, it will be found that the relics of previous 
tests, as far as they were still available, have been arranged to serve as technical 
exhibits — partly as out-door exhibits and partly indoor — and these collections are to be 
materially extended and catalogued. 

Fire Protection in Theatres. — A model theatre has been built at Dusseldorf, in 
order to test the dangers of theatre fires, and the best means of rendering theatrical 
buildings proof against fire. It occupies a site measuring 50 ft. by 80 ft., with the 
auditorium 30 ft. and the proscenium 40 ft. high. The main part of the building is of 
steel and reinforced concrete. A special entry enables observations to be made both 
in the front and the rear, and two kinds of fireproof curtains will be fitted. Seats 
are to be provided with the intention of testing various processes for rendering them 
fireproof. 

Raising Reinforced Concrete Walls with Jacks. — The accompanying draw- 
ings {Figs. 1 and 2) show the design and method of Operation of wall-raising 
jacks for reinforced concrete buildings and the structures in process of erection. The 
photographs, Fig. j, shows the officers' quarters as well as the barracks buildings at 
36S 



rTTcONSTUUCTlON; 
L<* ENGINEERING' 



MEMORANDA. 



Fort Crockett, Galveston, Texas, built in this manner, the latter buil 

1S7 ft. long and 58 ft. wide. _ 

The quartermaster's store-house- 116 ft. long- at Crockett was also 1 
manner the walls being raised into place in 4 i hours bj these jacks, rhe front 
of the post exchange and gymnasium building at Galveston, rexas, weighing 243 
was erected with these raising jacks 

Th. concrete walls of the Military Academy at San Antonia, Texas, were 

completed in a horizontal position, the reinforcement being readily employed with small 

2££ cost, and the completed walls raised into a vertical P^^^fi^ J ;;;,^ 

ness structure 60 ft. by 
60 ft., with two apartments 
on the second floor, was 
erected at a eosl of only 
$18,000, including plumb- 
ing and heating. This 
building has monolithic 
concrete walls, light courts, 
and roof. 

It is maintained that 
this system of reinforced 
concrete building construc- 
tion is a simple solution of 
the. concrete problem. The 
expensive wooden or metal 
forms often make the cost 
of a form-built structure 
very high. 

The weakness of a 
wall built in forms is 
caused by the horizontal 
stratas of cement, sand, 
and gravel, which result 
from pouring two or three 
feet (vertically) of a wall 
each day ; this is essential in 
form construction, while the 
length of time consumed in 
building forms and pouring 
cement in them is so great 
that many owners and 
architects are loath to 
undertake the proposition. 
It is held that all of the 
above-mentioned difficulties 
have been successfully over- 
come by this method. The 
system is simple and 
unique. On this and on 
piles inside of the building 
lot are set a series of steel 
jacks. These jacks consist 
of a supporting carriage, a 
pivoted walking beam, and 
a collapsible screw driven 
by a worm gear and worm. 
A platform is then laid on 
the jacks, and on this 
form an 9 ' in _ their 
proper relath ! posit 
all door-fr 
frames, and other openi 




Figs. 1 and 2. 



Now the concrete is poured around the openings of this construction. 



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UNIVERSAL JOIST 
STEEL SHEET PILI 



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Illustration shows cross dam at the Entrance to Chertsey Lock which is G-fO 
now being reconstructed by the Thames Conservancy. It is a jingle row 
of our 15 inch X 43 lb. Piling, and is quite watertight. The tame kind 
of piling is also being used for retaining the sides of the Lock, 
afterwards being covered with concrete and forming part of the 

permanent work. 

•h THE STRONGEST PILING 4> 
ON THE MARKET. _ 



> iS. The British Steel Piling Co. 4* 

Telegrams : 

Lond a o r cy Dock House, BiHiter Street, LONDON, E.C. 



X 



I — I — I — I — I — I — I — I- 



1? 



370 



Please mention this Journal -when writing. 



s 



CON5TKUCTIONAi;| 
ENQ1NEE.K1NG 



iNAD 



MEMORANDA. 



The reinforcemenl is easily and properly placed both horizontally and vertically, 
because the wall resembles :i great draughtirng-board, and is very readil " laid out." 

If an air space is desired, it is only to be lill<-d in with louse sand, whii h is removed 
before the wall isentirelyin place. When the entire wall is poured and thi don< 

in a single day, even though the wall be 200 ft. long and three stories high -and the 
finish desired is put on the outside surface, it is all level like a huge work-tabli . 

After the wall is finished, it is allowed to set for forty-eight hours; then a mall 
gasoline engine or electric motor is connected to the driving-shaft and the wall 
from the inside slowly and quietly to its permanent vertical position. 

The space between the wall and foundation is pointed up and properly braced, and 
then comes the removal of the jacks, which are bolted to anchors set in the wall. 




Fig. 3. Officers' Quarters and Barracks Building, Fort Crockett, Galveston, U.S.A. 



When all the walls are in place, the corners where reinforcement from either wall 
project and interlock are then poured, and there is a complete monolithic, well-finished 
structure. The floors and roof of concrete, or of any construction desired, are then put 
in in the same way as in any other building. 

No forms whatsoever are used in the wall construction excepting the wooden jack 
platform, which is never destroyed, but is used over and over again. The reinforce- 
ment is placed both horizontally and vertically exactly where it belongs in both inner 
and outer walls and rods. Fabric or any other kind of reinforcement may be used 
without the slightest difficulty. It is claimed that a building can be constructed in 
two-thirds of the time required for brick construction. 

Strength Coefficients of Reinforced Concrete Telegraph Posts.— The Service 
de l'Electricite of the Brussels Municipal College has informed the Union des Exploita- 
tions Electriques that its consultative committee on safety measures has adopted the 
following coefficients for telegraph posts made of reinforced concrete. When such 
posts serve to take wires across a railway, the concrete must stand a compression stress 
of 30 kg. per sq. centimetre (427 lb. per sq. in.), and the metal a tensile strain of 800 kg. 
per sq. centimetre (11,378 lb. per sq. in.), but when the telegraph line follows or crosses 
a road or waterway these figures must be increased to 35 kg. (4c)S lb.) and 1,000 kg. 
(14,223 lb.) respectively. — Contract Journah 

Buildings on Reinforced Concrete Raft.— Messrs. Cory and Son, Ltd., the well- 
known coal factors, have recently carried out a well-devised scheme for the provision oi 
dwellings for the class of unskilled labour employed at their coal derricks and barge 
works at Charlton. 

The site, of throe acres, is situated in the Charlton marshes, with a frontage to 
Anchor and Hope Lane. The eighty-two dwellings are arranged in two-floor self- 
contained flats, with separate entrances, grouped around secluded and gated 
rangles planted with trees. 

The accommodation of each flat consists of four, live, and six ro 
to meet the means and family requirements of the varying classes of I ' ' 



MEMORANDA, 



[OBCRETFJ 



in the coal industry. The nature of the foundation, which was a mud shoot 
several feet deep on a peat bottom, necessitated special precaution and a 6-in. rein- 
forced concrete raft laid over the entire site of the buildings. The absence of 
back-additions enabled the weight to be distributed evenly over the raft, and although 
some of the buildings have been completed over two years no sign of structural failure 
has appeared. — Building News. 

TRADE NOTICES. 

Corporation of Pontefract : New Baths in Reinforced Concrete. — Mr. A. 

Nunweek, of Sheffield, the architect whose design was accepted in open competition for 
the above, has decided to construct the baths, subways, floors, etc.. in " Piketty 
Concrete." The contract is being executed by Messrs. James Fkller, Ltd., of Sheffield, 
who are licensed contractors of Messrs. Paul Piketty and Co., Reinforced Concrete 
Engineers, 14, Bloomsbury Street, London, W.C. 

Harwich : New Landing Stage in Reinforced Concrete. — The Corporation 
of Harwich has decided to construct the new landing stage (length 250 ft.) in reinforced 
concrete, and has adopted the plans of Messrs, Paul Piketty and Co., Reinforced 
Concrete Engineers, London. 

The work will be carried out forthwith by Mr, T. W. Pedrette (licensed contractor 
for the " Pikettv System"), of Enfield, N., whose tender has been accepted. 



BRITISH IMPROVED CONSTRUCTION CO. 

Telephone: 4067 Victoria. LTD. Telegrams: " Biconcrete, Vic. London." 

" B I C " 
47 VICTORIA STREET, WESTMINSTER, S.W. 

Manufacturers of all kinds of 

Concrete Constructional Materials 

(Plain or Reinforced) 

Including PIPES, PARTITION AND PAVING 
SLABS, SLEEPERS, STANDARDS & POWER 
TRANSMISSION POLES, HOLLOW BEAMS 
AND FLOORS, FENCING POSTS, etc., etc., 

by the well-known "JAGGER" PROCESS. 

Engineers' and Contractors' Own 'Designs carried out to order 

SPECIALITY. — Reinforced Concrete Pipes for High Pressures, abso- 
lutely Impermeable. Our Concrete weighs 156 lbs. per cubic foot. 



372 



CONCRETE 

AND 

CONSTRUCTIONAL ENGINEERING 



Volume VIII. No. 6. London, June, 1913. 

EDITORIAL NOTES. 



THE CONCRETE INSTITUTE. 

ANNUAL GENERAL MEETING. 

The Annual General Meeting- of the Concrete Institute took place on May 22nd, 
when the report for the session 1912-13 was presented by the Council. This 
Report shows an increasing activity in the Institute's work during that period, 
and it certainly indicates the wide scope of its usefulness, if full advantage is 
tactfully taken of the great technical talent to be found among the membership. 
This we do not think has been the case during the last few years, otherwise 
there would not have been so many resignations from its Council, and, what is 
more, the retirement of just those members who would be among the most 
valuable and experienced available. 

Last vear the Council lost a number of most useful men, and this year we 
find that men like Mr. Bertram Blount, F.I.C., and Mr. C. H. Colson, 
M Inst C.E., of the Admiralty, are giving up their seats. When men of this 
character retire it is always a sign that the Council meetings do not 
really interest them, or are looked upon as a waste of time. An uninteresting 
Council meeting is practically a sure indication of one devoted too largely to 
administrative routine as distinct from technical advancement, and, maybe, 
this is the case when we read of the Institute again changing its rules, re- 
arranging its objects, and classifying the membership when there is so much 
useful and technical work to be achieved. Surely these continuous changes 
are not necessary. 

But it is very obvious from the report that the real work of the Council is 
actually done by the Standing Committees, comprising partly members of 
Council and partly members co-opted from the general membership. 

It is a healthy sign to observe the extensive work done by these com- 
mittees and the comprehensive character of the problems still under considera- 
tion It seems to us that it is the Committees rather than the Council that 
are upholding the dignity and advancing the interests of the Concrete Institute. 
Particular congratulations should be accorded to the Science Standing Com- 
mittee, which is certainly doing most admirable work. 

As to the recent tendency to make the Concrete Institute what might be 
termed an "Institution of Structural Engineers," the idea being to gn 
"Concrete" per se a subordinate place, we note that no very great advan 
ment has fortunately been made in this line of thought. The Institute 
obviously deal with much that relates to structural engineering, bul 



THE CONCRETE INSTITUTE. [CONCRETE 



to hold its own il should he the Concrete Institute and nothing else, and if 
so-called engineers are really desirous of having their own little society, there 
is ample opportunity for some active genius to form such a body without 
entrenching on the greater and more influential bod}- whose interests are 
dircctlv concerned with that vast subject covered by the title of " Concrete " — 
a subject, by the bye, which is rapidly becoming quite as great as the subject 
of iron and steel, dealt with by the Iron and Steel Institute, an association also 
connected with the subject of structural engineering. 

It is pleasing to observe that the membership is increasing, and with the 
honorary members the figure of 1,000 has been reached. But quantity alone 
does not make an influential membership, and thus the Institute would be 
very well advised to be more careful than it has been in the last two years 
in the acceptance of candidates applying for enrolment. 

Financially the Institute has done remarkably well, and congratulations 
should be specially accorded in this direction to the President, Mr. E. P. 
Wells, who, by careful economy, has kept the expenditure within the Institute's 
resources. Being essentially technical, rather than humane in its objects, the 
Institute cannot rightly have claim either to the enthusiasm or the charity 
of those benevolently inclined to help Science and Humanity. To do really 
good work the present income of ,£'1,000 requires increasing to ^2,000, and 
whether eventually it will not be wise boldly to take the grave step of even 
increasing the subscription for existing members is a matter which certainly 
claims consideration. 

Speaking generally, therefore, excepting for a certain loss of the Council's 
prestige of late, the Concrete Institute has made good progress, and, given 
greater energy, there is no reason why the impending year should not be more 
successful than the year that has past. 

THE LOCAL GOVERNMENT BOARD AND REINFORCED CONCRETE. 
Ax interesting feature in the Annual Report of the Concrete Institute is 
the reproduction of the letter from the Local Government Board to the 
Concrete Institute on the matter of the Repayment of Loans in respect of 
Works of Reinforced Concrete Construction. 

This letter, dated April 14th, 1913, is printed below, and we reserve our 
observation for a future occasion : — 

I am directed by the Local Government Board to adyert to your letter of the 
28th ultimo, with reference to the period allowed for the repayment of loans 
sanctioned by them to local authorities for the construction of works of reinforced 
concrete, and I am to state that the Board have fixed no single period. Each 
case is dealt with on its merits, haying regard to the purpose of the work and 
its position. Generally speaking, however, the following terms are taken as a 
basis in calculating the periods to be allowed in respect of the more common 
terms of ferro-concrete construction : — 

Bridges with flat super-structure properly protected by a layer of asphalte 
or other suitable material ; reservoirs and tanks containing liquid — 10 years. 

Arched bridges protected from moisture by .1 layer of asphalte or other suitable 
material; chimney shafts; tubes— 15 years. 

Floors of building subjeel mostly to dead loads and properly protected from 
electric currents and damp — 30 years. 

374 



SOUTH LAMBETH GOODS DEPdT 




SOUTH LAMBETH GOODS 
DEPOT. 

By ALBERT L\KEMAN. 

One of ihe most interesting applications of the use of reinforced concrete in structural 
•work is its extensive and increasing use for railway work of every description, and the 
following article on the South Lambeth Goods Depot contains many coints of special 
interest. — ED. 

These large premises have been erected for the Great Western Railway Com- 
pany in South Lambeth on a portion of the site formerly utilised by the Vauxhall 
and Southwark Waterworks Company for filter-beds from the designs of 
Mr. W. Armstrong, M.Inst.C.E., the engineer for new works to the Great 
Western Railway. 

The premises include a large goods station and warehouse, office buildings 
and stables, together with numerous sidings and tracks for the traffic and also 
storage purposes, the whole scheme providing splendid facilities for the collec- 
tion and delivery of goods in 
South London. Direct com- 
munication is afforded with 
the Great Western Railway 
system via Battersea and 
Acton, and connection is also 
given to the various railway 
systems passing through Clap- 
ham Junction. 

Many interesting con- 
structional features are to be 
found in the buildings, par- 
ticularly in the goods station 
and warehouse portion, the 
material used being reinforced 
concrete designed on the 
Hennebique system by Messrs. 
L. G. Mouchel and Partners, 
of Westminster, the minimum 
number of supports being used in the ground floor to avoid obstruction in the 
loading and unloading of the goods. This main building is about 400 ft. long 
by 72 ft wide, and it has a total height of 80 ft. from the foundation level to 
the top of the parapet. 

The accommodation provides a basement for storage purposes ; a ground 
floor, which has a height of 36 ft. 4 in. from the lewel of the railway lines 
first floor level, and three upper floors for the storage of goods, the topmo 
being constructed over portions of the building only in the form of three 

b 3 75 




Fisi. 1. Typical Column Detail. 
South Lambeth Goods Depot. 



ALBERT LA K EM AN. 



[CONCRETE] 




each j 2 ft. by 53 ft., thus 
allowing for a future ex- 
tension if required. The 
flat roofs have also been 
constructed of sufficient 
strength to carry goods 
that may be placed upon 
them, and the storage 
area is therefore very ex- 
tensive. 

The building is con- 
structed as a reinforced 
concrete frame building, 
all the weight-carrying 

members beinp- of this 

r • 1 j 1. 

material, and the ex- 

u 

J ternal walls themselves, 

Cl, 

t> which are of brickwork, 
g are carried by reinforced 
u concrete beams. The 

V H 

c <p basement floor is about 

£ (5 2 ft. 6 in. above the 

3 §' underground water level, 

o and the underside of the 
rt h column bases is 4 ft. be- 

1 I low the basement floor 
-a ffl " level, or 1 ft. 6 in. below 

•S £ the water level. The 
x w basement floor is sur- 
J rounded by reinforced 
~ concrete retaining walls, 
l[ which are protected with 
- clay puddle to prevent 
the percolation of water, 
these walls having a 
height of about 13 ft. or 
15 ft., and being con- 
structed 5 in. thick, well 
reinforced in all direc- 
tions and stiffened with 
counterforts 1 2 in. 
square at intervals. 

The foundation to 
the wall consists of a 
projecting toe 8 in. thick 
and 3 ft. in width, with 
bars in both upper and 
lower surfaces. A hori- 



376 



[^^n^rTn/^ SOUTH LAMBETH GOODS DBP6t. 

zontal In am is formed at the top of the wall to carry the ends of the beams 
supporting the platforms, and this is about 18 in. square. The foundations to 
the columns were generally of two si/c-- v i/.. ( about u ft. to 14 ft. square For 
the main columns, which extended through the ground floor to carry the main 
loads of the building", and about <> ft. by 2 ft. (> in. for the remaining columns, 
which occurred for the height of the basement floor only. 

The type of base adopted consisted of a slab having a minimum thickness of 
7 in. to 1 1 in., splayed up towards the column to give a maximum thickness ,i 
the intersection of from 21 in. to 44 in. to provide the requisite shearing area. 
The reinforcement consisted of two sets of rods, each set having bars in both 
directions, and these were connected to each other and the mass of concrete in 
the base bv numerous stirrups, with additional distribution bars at the bottom 
of the vertical reinforcement to the column. The whole of the bases were 
designed to give a uniform pressure per square foot on the soil to prevent the 
possibility of unequal settlement. 

The arrangement of the columns is interesting, as will be seen from the 
half plan of the ground floor construction (viewed from below), which is 
illustrated in Fig. 2. The smaller columns shown are those which occur on the 
basement floor only, and these are spaced in three longitudinal rows in the 
interior at distances apart equal to 13 ft. 3 in., while there are only two rows of 
main columns, and these are spaced at 26 ft. 6 in. centres. The width between 
these latter columns is about 58 ft., and they carry the whole of the super- 
structure, thus bringing a large load upon each one. The section employed is 
2 ft. 9 in. bv 2 ft. 6 in. at the basement level and there are no less than 36 bars 
used as the vertical reinforcement for each column, these being arranged in four 
groups of nine bars situated at the corners, and connected by steel links in all 
directions, as shown in Fig. 1. These columns are reduced to 2 ft. 9 in. 
bv 2 ft. 3 in. at the ground floor level, with a further reduction to 16 in. sq. 
on the first floor, and they are protected with steel sheathing attached to 
angle steels at the corners to prevent damage when knocked by heavy goods. 
The smaller columns in the basement are 14 in. square in section and reinforced 
by 4 lines of vertical reinforcement, with steel links at intervals. The spacing 
of the beams at the ground floor level is shown on the plan mentioned previously 
and these consist of main and secondary beams. 

The tracks between the platforms are carried by secondary beams, 
four being placed under the rails, and these are about 1 ft. 7 in. 
deep and 7 in. wide, and all four beams are connected to and 
carried by main beams which are 1 ft. 11 in. deep, 9 in. wide, and span 
between the columns at 13 ft. 3 in. centres. The slabs filling in the panels 
are 5 in. thick, and this is included in the depth of the beams as given; while 
haunches 12 in. deep and 2 ft. long are provided on the main beams at the 
junction with the columns. The distance between the platforms is 32 It. jh in. 
and these have widths of 10 ft. and 25 ft. respectively, the former having a pro- 
jection of 2 ft. beyond the line of the main columns and the latter having 
a projection of 12 feet. 

Apart from the variations necessitated by staircases and weighing machines, 
etc., these platforms are carried by beams at the inner edge, beams between tl 



ALBERT LAKEMAN. 



[TONC RETEi 



columns and the beams at the top of the retaining wall on t lie outer edge, 
together with srraller transverse btams supported on these spaced at 4 ft. 5 in. 




Fig. 3. Interior View of Basement. 




378 



Fifi. 4. View during Construction. 
South Lambeth Goods Dep6t. 



f j. CONM kMICTlONA 



m 



SOUTH LAMBETH GOODS DEPdT. 



centres. The platforms are .ill 4 in. ihick, and the outer edgi - of the 
platforms on the roadway side are protected by heavy cast-iron curbs. A view 




Fig. 5. Reinforcement for Large Beam in Position. 




Fig. 6. Interior View of Goods Station. 
South Lambeth Goods Depot. 






ALBERT LAKEMAN. 



[CONCRETE 



showing the basement floor during- construction is illustrated in Fig. 3, where 
the main and secondary beams, together with the metal sheathing to the 
columns, can be clearly seen. The work to the platforms, etc., can also be 
seen in the photograph taken during construction and illustrated in Fig. 4. 

The floors above the ground floor are constructed to carry an external load 




t--d t--J 

Fig. 7. Cross Section of Goods Station. 
South Lamrf.th Goons Depot. 



of 3 cut. per ft. super, and here the secondary beams are spaced at 4 ft. centres 
and the filling is 3 \ in. thick. 

The most interesting features are the large main arched beams 
which occur at the first floor level and span transversely across the station 
between the main colrmns and cantilever a distance of 12 ft. cj in. beyond the 

380 



l&^JNiSffg ] SOUTH LAMBETH GOODS DEPdT. 









line of tiics-.' columns ;ii the southern end. These beams are i ei tain >me of the 
longest constructed in reinforced concrete, the total length being about 72 ft., 
and their greal advantage will be apparent, as there are five rows of columns 
on the upper floors, two of which are carried by cantilever projections, one 
continued up from the line of the main columns and two supported by the 1 entral 
span of the beam. It would have been inconvenient and inadvisable to continue 
all these columns through the ground floor, and by the method adopted the 
columns were reduced to two lines only. The beams are arched and have a 
depth at the centre of 7 ft., and 8 ft. 9 in. at the junction with the columns, 
inclusive of the thickness of the floor slab, and the width is 2 ft. In order to 
reduce the (.\c-\d weight and improve the interior appearance of the station the 
thickness of the web is reduced to form four panels, each 9 in. thick with 
stiffeners 2 ft. wide between same. The beam therefore becomes practically a 
flanged section, the tension flange, which is arched, being 2 ft. by 1 ft. 6 in., 
and the compression flange 2 ft. by 1 ft. 9 in. A drawing of this beam is 
illustrated in Fig. 9, and it will be seen that the reinforcement consisted of no 
less than eighteen bars in the compression area and twenty bars in the tension 
area, with numerous links for connecting the bars and stirrups for resisting the 
shear. Some of the shuttering with the reinforcement in position is shown in 
the photographic view illustrated in Fig. 5; but it was impossible to obtain a 
view showing the whole of the steelwork in position owing to the obstruction 
of the woodwork. 

Longitudinal beams 9 ft. 3 in. deep and 1 ft. 8 in. wide are also 
constructed between the main columns and at the outer end of the canti- 
levered portions, thus tying the whole construction together and forming a 
rigid structure. These beams also have the webs reduced in thickness to 10 in. 
to lessen the dead weight to be carried. This building is quite unique arid gives 
an excellent idea of the possibilities of reinforced concrete, the whole of the 
upper part being carried on the few main columns and projecting' beyond these 
on either side, giving a curious effect, as will be seen in the section illustrated 
in Fig. 7. A general view of the structure when practically finished is shown 
in Fig. 8, and some idea of the length can be gathered from this. 

The western end of the station is filled in with galvanised iron carried by 
steel framing, with the necessary opening for the passage of the trains. At 
the south side of the building the van roads and railway tracks are covered 
bv steel-framed roofing, 48 ft. wide, for protection against the weather, and 
the steelwork is connected to the reinforced concrete work with Lewis and rag 
bolts, and in some cases reinforced concrete wall plates are utilised to carry the 
ends of the trusses. In addition to the goods station herein described, rein- 
forced concrete was employed for the columns, floors and staircases throughout 
the office building, which is about 83 ft. long by 41 ft. wide, and consists of 
basement, ground, first and second floors, and also in the stable building, 
which is designed with an L-shaped plan, the main portion of which is 136 ft. 
long and 28 ft. wide, and the secondary portion 54 ft. long by 28 ft. wide. The 
latter has a special covered sloping way for the traffic of horses t > the upper 
floor, which is designed to carry an external load of i\ cut. per sq. ft. 
sloping way is supported on reinforced concrete columns spaced at 13 ft. 3 in. 
centres, and the floor and roof beams and slabs are constructed with similar 
material. 



ALBERT LA REM AN. [CONCR ETE] 

I he whole scheme is a most complete one, and adequate equipment is 
provided in the station for the hauling of trucks and hoisting of goods, the 
cranes being carried in some cases by brackets which project from the main 
columns, and two movable bridges are provided for the transfer of goods from 




one platform to the other, these being similar to those which have been in use 
for many years at Paddington Station. 

The contractor for the work was Mr. A. X. Coles, Plymouth. 



382 



G.W.R. SOUTH LAIN 




V\k. 9. Detail of Arched Beam over Ground 

i m ,,,1111 Lambeth Goods Depo-; 



I. SOUTH LAMBETH GOODS DEPOT 




I letail oi Ai. bed Beam over Ground Floor. 
i Sou i'h i..\\ bi hi Goods De ?< ■ i 






c 



f y , CON.STPUCTIONAr! 
1A ENGINEERING -^1 



CRACKS IN CONCRETE. 



■±H 



~m I 



ill 




CRACKS IN CONCRETE 

AND 

$ SURFACE TREATMENT y$ 

BEING 

TWO REPORTS 



1 




CONCRETE PRACTICE STANDING COMMITTEE OF THE 
CONCRETE INSTITUTE. 

W<? present herewith the two following reports recently issued by the Concrete Institute 
on the very important questions of "Cracks in Concrete" and the "Surface Treatment 
of Concrete." An interesting discussion followed, of which we are only able to give the 
barest outline, but, as mentioned in the report of that discussion, we earnestly hope the 
Sub-Committee responsible for these reports will take heed of the various criticisms ana 
suggestions thrown out, for excellent as the reports are in many ways, they require consider- 
able amendment and elucidation before they are finally approved by the Council.— ED. 



In June, 1909, the Reinforced Concrete Practice Standing Committee of the Concrete 
Institute issued letters of inquiry to all the members of the Institute in order to obtain 
information concerning Cracks in Concrete and the Surface Treatment of Concrete. In 
nplv to these inquiries some fifty-four letters were received regarding the Cracking of 
Concrete and forty-six letters regarding the Surface Treatment of Concrete. 

The Reinforced Concrete Practice Standing Committee have now issued two 
reports setting out a review of the subject, together with recommendations. These 
reports were read at the Institute's thirty-sixth ordinary general meeting, followed by 
a short discussion. They read as follows : — 

REPORT ON CRACKS IN CONCRETE. 

The cracking of concrete is unsightly, but is not necessarily dangerous. Cracks in 
concrete may be divided into two classes : — 

1. Surface cracking. 

2. Body cracking. 

In the first category the cracks are often referred to as " hair " cracks, bv reason of 
their fineness and semblance to hairs, and occur both in plain and reinforced concrete. 
They are also known as " crazing " and are of very frequent occurrence. They appear 
to arise from the surface skin of cement mortar being richer in cement than the mortar 
of the body concrete, thus exposing almost a neat cement skin, which expands .it a 
different rate on exposure to the sun's rays than the body concrete. It is worse upon 
the uppermost face in a mould, where the lighter and weaker particles of cement work 
up to the top and form a skin known as "laitance." If work be kept under water, 
and sometimes, if shielded from the sun, this crazing may not occur. To overcome its 
unsightliness the surface skin should be removed either (1) by brushing the concrete 
when green with wire brushes; (2) by rubbing by means of a stone or piece of concrete 
and sand and water; (3) by dressing with hand or pneumatic operated chisels and 
hammers; (4) by brushing the surface with hydrochloric acid and subsequent washing 
with clean water. The last two named methods are best with completely hardened 
concrete. 

The cracks extending through the body of concrete may be ascribed to the 
following : — 

1. Faulty design and construction so far as statical resistance is concerned. 

2. Expansion of cement or concrete. 

3. Corrosion of embedded steel. 

4. Shrinkage from setting and hardening in air. 

5. Difference of temperature in different pa.t-. 
c 



CRACKS IN CONCRETE. [ CONCRETE] 

i. Under the first head the following causes have been noted : — 
(a) Settlement of the foundations. 
(/>) Too high a stress in the reinforcement, resulting in excessive deformation. 

(c) Too thick a covering of concrete, in particular where the effective depth of 

beam> is very small. 

(d) Too earlv removal of forms. The age of the concrete when the forms are 

removed must be sufficient to give the usual factor of safety due to the 
stresses caused by dead load and such accidental load as may at that time 
be anticipated. Generally the following recommendations are made, 
subject to the approval of the engineer or architect responsible for the 
work-. 

For mass concrete walls not subject to thrust, and where the height does not 
exceed 2 ft., the forms should not be removed under 24 hours. Where the 
wall is subjected to pressure, forms should remain in place at least a week, 
although a fortnight is preferable. For mass concrete arches of more than 
20 ft. span one month is recommended. 

For reinforced concrete the following is recommended : — 

Slabs, a minimum of 7 days, but otherwise, for slabs carrying only their 
own weight, an allowance of 2 days per inch of thickness, or 1 day per foot of 
span, whichever is the greater. For sides of beams, walls, and columns not 
under side-thrust a minimum of 4 days; bottoms of beams, a minimum of 
2 weeks, though a month to 6 weeks may be necessary under special 
circumstances ; for arches the time of removal of the centering is better left 
to the judgment of the engineer, keeping in view the ratio of rise to span 
and special circumstances. 

If it is intended that the structure should be used for carrying heavy 
weights, emergencv props should be left in for such time as the engineer 
or architect may direct. 

The foregoing periods to be increased by at least the time during which frost 
or rain has intervened. 

(e) Defective design of forms with inadequate allowance for contraction and 

expansion due to variation of moisture. Dry timber may expand and 
crack the concrete unless wetted beforehand. 

(/) Careless removal of forms, which may result in cracking the concrete by 
shock of falling timber, or by levering and prising on the green concrete. 

(g) Vibration, resulting in deficient adhesion and excessive deflection. Form- 
should be very rigid. 

(h) Insufficient allowance for continuity, fixity, and general monolithic nature 
of concrete work done in situ. Over supports the maximum degree of 
continuitv and fixity should be provided for. Frequently cracks will be 
found over supports of continuous reinforced concrete beams and floor 
slabs, owing to the omission or insufficiency of steel there. Concrete floors 
are often built in chases in walls and carried over walls, others standing 
above, and sufficient fixitv is given to cause cracks, if provision has not been 
made in the reinforcing. Columns and piers when built monolithic with 
beams will give more or less fixity to end of beams resting thereon, both 
at end and intermediate supports. 
(i) Too close spacing of steel, so that there is no room for the concrete to get 
round and adhere or bond with the bars. 
2. Expansion of cement or concrete. 

Under this heading the following causes of cracking are noted : — 

(a) Overtimed and coarsely ground cements which wen' frequently met with 

years ago caused expansion, to overcome which it was necessary to leave 
room lor expansion — i.e., expansion joints. Especially was this precaution 
adopted round the edges ^i floor slabs adjoining walls. 

(b) Coarse materials containing suiphur compounds, unburnt fuel, oxidisable or 

hvdratable iron compounds, unslaked lime, and other del< terious substances. 
Breeze, clinker, ami slag frequently contain sulphur and metallic iron or 
oxide of iron, while boiler ashes may contain both sulphur and unslaked 
lime (the latter derived from limestone in the coal). Some bricks contain 
38 + 



*^S^j CRACKS IN CONCRETi:. 



sulphides and sulphates and lime, and should nol b< used broken for 
concrete. Old bricks also sometimes have old plaster adhering to tl 
the sulphate of lime may cause no trouble in plain concrete while ii is 
dry, bm in the presence of water reacts chemically with the aluminafc 
ilic Portland cement, forming sulpho-aluminate ol lime, which is attended 
by increase in volume, and may cause blowing if in large quantity, and 
even a small quantity may result in cracking. Free lime in the same way 
will swell or contract with water. Black magnetic oxide of iron will become 
converted into hydroxide of iron in the presence of moisture. Indeed, any 
iron compounds are dangerous in reinforced concrete as likely to react 
electrolytically with the steel in the presence of moisl air or dampness, and 
sulphur causes speedy corrosion. 

3. Corrosion of embedded steel. 

Should the steel in reinforced concrete corrode by reason of porosity of the concreti 
or the presence of deleterious substances in the coarse materials of which it is made, or 
by electrolytic action, the concrete cover to the bars will crack and burst off. 

4. Shrinkage from setting and hardening in air. 
This is probably the most frequent cause of cracking. 

Concrete will expand slightly in water and contract on drying out, so that cracking 
is frequently not evidenced from this cause until the concrete is allowed to dry, varying 
usually up to two months, and in thick mass walls moisture and heat are retained For 
a long period and may delay cracking' up to six months and even longer. It is usual 
to keep concrete wet for several days after manufacture in order to ensure its gaining 
maximum hardness, and it is specially important to prevent rapid drying by sun and 
wind, so that the surface of concrete should be shielded against such exposure. A dry 
mixture of concrete shrinks less than a wet mixture, and concretes richer in cement 
contract more than lean mixtures. For reinforced concrete work medium wet mixtures 
are desirable, and therefore concrete richer in cement than 1 to 5 is not advisable for 
curtain walls. The coefficient of contraction of concrete on exposure to air appears to 
be about 0*0002 to 0*0005 at one month, and increases to about o"oooq to o - ooo6 at 1^ 
years. The variation recorded is between poor and rich concretes. Such contraction is 
usually prevented from taking place uniformly throughout; in retaining walls and 
pavings it is prevented by friction of the soil, in other cases by the holding of other 
parts. Plain concrete will usually hold together for some distance, so that contraction 
joints need only be inserted at intervals; the following are advised as suitable distances 
apart of such joints in plain concrete : — 
Paving, 4 to 5 ft. 
Curtain walls, io ft. 
Exposed retaining walls, 15 to 20 ft. 

Basement retaining walls (not exposed) and dock walls or dams, 50 ft. 
If curtain walls adjoin heavy columns and beams, the rigidity of the latter would 
probably result in cracking if constructed monolithically, even if reinforced. It is best, 
therefore, in such cases to provide joints adjoining beams and columns. 

If concrete be laid over the joints of a thicker lower surface of concrete, the joints of 
the latter will most probablv be evidenced in the upper surface. 

Sharp angles in structural members have little resistance, and should be avoided, 
as also irregular shapes. The angles of window openings, unless well rounded, should 
be reinforced by bars placed diagonally. 

As the rate of shrinkage varies with different proportions of the concrete ingredients 
— cement, sand, coarse material, and water- -variation in such proportions should be 
avoided as much as possible. Cracks in plastering are often (.\uv to such irregular 
contraction. 

Partition and wall blocks, if required to be plastered soon after laying, should be 
quite dry before laying. If erected wet, the plaster should not be applied until they haw 
had good time to shrink, otherwise the joints of the blocks will show as cracks in the 
plaster. 

Large surfaces have been successfully constructed without apparent cracks 
properly reinforcing the concrete and laying all at one operation. The objeel of the 
reinforcement is to break down the tensile resistance of the concrete and caus< it to 

crack uniformly al such close distances as to lender the cracks invisible to :' 

c 2 38 5 



CRACKS IN CONCRETE. [CONCRETE) 

If one portion of the concrete be left overnight, great can- should be taken to roughen 
the hardened surface by tooling away; then clean by brushing with water, and apply 
half an inch of mortar of the same proportion as the mortar in the concrete and ram 
the fresh concrete well against it. Such joints will often show, even though well 
reinforced. In calculating the amount of reinforcement for such purpose, the ultimate 
tensile strength of the concrete at one month should be equated to the resistance of 
the steel at the yield point. Usually for a i : 2 : 4 concrete 5 per cent, of steel is required 
each way, the bars or meshwork being laid at right angles. The reinforcement should 
be in small sections and well disseminated through the thickness of concrete, and a 
layer of bars should be near each face. So-called " distribution bars " near the bottom 
of floor slabs are not sufficient if cracking is to be resisted ; rods should also be placed 
near the upper surface. Cracks frequently occur parallel to rods where " distribution 
bars " are not used, and also occur at right angles to main bars where continuity bars 
stop; top reinforcement would avoid this. Contraction reinforcement should be in 
addition to the section of steel required to resist static forces. 

The sudden drying out when heating apparatus is installed frequently causes 
excessive cracking. 

5. Difference of temperature in different parts. 

Considerable difference of temperature will cause cracking and should be avoided 
as much as possible. Heavy reinforcement is not always an effectual preventative. 
Most reinforced concrete chimneys in which the internal temperature is over 500 F. 
seem to be cracked vertically, externally, and often horizontally as well, though 
possibly the latter could be avoided. This cracking is probably due to the difference in 
temperature between the outside and the inside, which may be considerable with a cold 
wind blowing. A continuous lining with cavity between it and the outer shell would 
probably prevent serious cracking. 

Great difference in the temperature between the underside and top of concrete 
floors is also likely to cause serious cracking. In some climates the variation in 
temperature is extreme and cracks will result, and even if reinforcement is provided 
it will be well to insert expansion and contraction joints every 50 ft. 

Concrete lining, and walls of ponds, tanks and the like exposed to water do not 
shrink by setting and hardening of the concrete, but change of temperature between 
summer and winter will cause cracks unless joints are provided. If plain concrete, 
a joint every 15 ft. is desirable ; if reinforced, joints might be 50 ft. apart, though 
closer is preferable. To prevent percolation, asphalt dowels in the joints have proved 
efficient. 



REPORT ON SURFACE TREATMENT OF CONCRETE. 
(Summary of Replies Received.! 

i. Rough-casting is the best finishing coat for exterior finish. In applying a 
cement rough-cast, however, a bonding material should be used to insure adhesion to 
the old concrete. For floors, stairs, walls, and internal finish generally, tiles and 
granite finish may be employed ; there, also, the use of a bonding material is advocated. 

2. Blue stone dust trowelled to a glass face before the cement is set is advocated 
for facing the concrete, without any rendering. 'For rendering mortar composed of 
1 part of sand to 1 part of pure Portland cement is advocated with trowelled finish. 

3. In surfacing the concrete without rendering it is advised that the surface of the 
mass concrete should be beaten down level and smoothed with a wooden or metal float 
jusl as ii is beginning to set according as to whether a dead or bright surface is desired. 
Jt should never lie faced, as is often done, by the application of a thin skin of a finer 
material, which, when applied if the mass has partly or wholly set, marly always 
comes off. Micaceous, clayey, silly, or ochreous sand or gravel should be avoided, 
particularly micaceous sand, the mica in which, if the concrete be much worked, rises 
to the surface and causes constant dusting. If a floor is to he faced with a liner or 
richer class r>l concrete, then use that used lor the body. The best results are obtained 
by laying the body and face at the same time, the lacing portion being laid on the top 

before it has set and being well beaten down into it. Exposed concrete laces should 
never he much wroughl or polished with a metal tool, as the resulting dense smooth 
skin invariably develops hair cracks, which are unsightly. In moulded work the face 

386 



■ ENGI N L.ER1NG---J 



SURFACE TREATMENT OF CONCRETE. 



iK'\t to the mould may be made of finer material it the concrete is mixed ven di 
the facing' material be made soft and the dry concrete, before ramming, be held back 
with a shovel placed between it and the mould; the subsequenl ramming will cause this 
face to unite with the body, [f a facing material is not used, the concrete should be 
mixed plastic and worked up and down and to and fro with a shovel, trowel, or rod all 
along the faces which are to be exposed, and particularly along the arrises. Concrete 
tor such work requires to be properly proportioned so as to be without voids. On 
removal of the forms any roughness may be removed by rubbing with a pi* 
sandstone and water, or the face may be rubbed with a mixture of sand and cement 
by means of a wooden float, but this latter is not recommended if oil or soap has been 
used on the moulds, as the thin skin frequently fails to adhere and weathers off. If 
rendering is employed, Portland cement or clean gritty sand or tine gravel is the best; 
the cement should be so* proportioned as to rather more than fill the voids in the 
aggregate. It is not desirable to render with neat cement, as hair cracks generally 
ensue. The surface to which the rendering is applied should be as rough as possible, 
quite clean and free from grease, mud, or dust, and, if necessary, it should be washed 
with a hard-bristled brush. If at all of a porous character, the surface should In- 
saturated with water before the rendering is applied. Portland cement rendering should 
never be applied to surfaces of materials containing sulphates; in one case a floor 
made of plaster rubbish and hydraulic lime was covered with an inch of excellent 
Portland cement rendering which parted from the floor wherever patches of plaster had 
come to the surface of the body. In another case rendering was applied over a rough 
coat of plaster-of-Paris, and all came off in large sheets. For colouring concrete or 
rendering care is necessary in selecting colours; Venetian red and Indian red should 
never be used, as they are always in practice heavily loaded with calcium sulphate, 
which often causes the cement to disintegrate. Red haematite, some red ochres, and 
many other of the iron ores, particularly if burnt, are safe and suitable. Red haematite 
has a very powerful effect, very little being needed. Yellow ochres are suitable and 
safe, and have considerable colouring power. Burnt umber is safe, and gives a nice 
warm colour. A satisfactory colour has not been found in blue or green ; copper 
arsenide gives a fair green, but it is not desirable. Ultramarine is unsafe. Black 
oxide of manganese is probably best, but it is not possible to get a clear black. Ground 
hard-burnt coke may be used, but it is not so good. Ground coal or lamp black is 
quite inadmissible, except in the case of some of the anthracite coals. A clean white is 
not obtainable, but a near approach may be made by using slaked white lime ; the lime 
carbonates on the surface and forms a permanent, almost white, colour. A cream 
colour which looks very well may be obtained by using slaked lime with a little yellow 
ochre — chalk and whiting do net give very satisfactory results. In all cases but that in 
which slaked lime is used, the colour in sufficient quantity to give the desired tint should 
be mixed (preferably ground) with the dry cement. Hand mixing is not satisfactory. 
In the case of slaked white lime, this should be freshly made, but perfectly slaked, and 
should be mixed with the cement and aggregate at the time of using. By blending 
the colours named, all usual building material shades of red, brown, buff, and grey may 
be obtained, and they are all permanent and safe. 

4. A facing mixture, usually two parts of sand to one of cement, put in the mould 
against the face of the form with the concrete behind it, has been found satisfactory. 
For colouring such a facing ochres have been found satisfactory, especially if used in 
excess; they have apparently little effect on the durability, and with a white cemenl 
a little colour goes a long way. Greys of all shades can be obtained by admixture of 
lamp black. All the colours seem to fade until the work is matured, but afterwards 
stand perfectlv well. The ultimate colour can always be found by experiment. 

5. A good sound skin can be obtained by specially tamping the concrete against 
the shuttering. All seams or joints between successive lifts require special attention : 
(<!) to break the old hard surface of the previous lift; (6) to make a good bond or bed 
of wet mortar between the old layer and the new into which bed the new concrete c.w^ 
settle; and (c) to ensure the rigidil\ of the shuttering across the joint so as to prevenl 
movement and consequent " lipping." If the surface be pitted with small air-holes, a 
mixture of tine sharp sand and cement proportioned 2 : 1 should be applied with a larg< 
brush and immediately rubbed into the surface with steel trowels or floats. The 
rubbing should be done with energy and continued until the holes are completelv 



SURFACE TREATMENT OF CONCRETE. [CONCRETE ] 

filled and all superfluous plaster rubbed off, leaving the old skin exposed. In this way 
the holes or pores will be conipleteh filled and the skin watertight, and disintegration 
under the influence of frost prevented, while at the same time it is not noticeable after 
the work becomes hard. The principal item of cost other than labour is the number 
of steel trowels used up. The final surface, it should be particularly noted, is not a 
plastered skin. 

6. If rendering be used, it should be proportioned 2 of sand or very fine aggregate 
to 1 of cement ; in no case should neat cement be used. The rendering should be 
applied to the mass of concrete as soon as the shuttering has been removed and before 
the surface has become hard set or carbonated by exposure to the atmosphere. Facing 
the concrete without rendering is advisable. For colouring, the following materials 
may be used: peroxide of iron, manganese dioxide, ultramarine, anhydrous chromium 
oxide, red ochre, yellow ochre, Chinese red, and crimson lake. 

7. The most satisfactory way of facing concrete in situ without rendering is to 
apply a plaster in the form of cement mortar against the shuttering, as the concrete 
is put in, keeping the plaster a little higher than the concrete and carefully working 
the latter into the mortar all in one operation. For rendering 1 : 1 sand and cement 
mortar has been found satisfactory. Rendering undoubtedly gives a better appearance, 
but it very often fails, mostly through frost. Good colour effects have been produced 
by a sort of stucco, stones being placed by hand in the soft rendering, but such work, 
to be durable, has to be performed slowly, and is, therefore, costly. The ordinary 
method, called " slapdash," is not considered durable. 

8. It is preferable not to render at all, but to work the concrete against the 
moulds; for very superior work stout iron moulds, highly polished and perfectly true, 
are advocated. For colouring, metallic colours such as red oxide are preferred to such 
substances as red ochre. 

9. The use of shell sand makes a pretty finish, but this cannot be obtained every- 
where; in Jamaica the sea beach is strewn with broken shell which looks like sand at 
first sight. For appearance coarse sand is preferable. Buildings tooled all over have a 
good appearance. The finish might be obtained by pneumatic chiselling or even 
carborundum wheels. The application of a face of \ in. of 2 : 1 mortar the same time as 
the bulk of the concrete is put in behind is advocated. For rendering 2 : 1 mortar with 
about 5 per cent, of clay in the sand is satisfactory. Rendering should be applied as 
soon as the moulds can be removed. In the case of bridge work, where the concrete is 
set before the laggings can be removed, the concrete should be kept wet for an hour or 
so before rendering. 

Black lead applied to the face of the concrete immediately it is in position will 
render the concrete when set practically indistinguishable from blue Staffordshire bricks. 

10. Rough-cast may be advantageously used, tinted or otherwise. 

n. For residential or street architecture cement finish is best, and can be varied 
almost to any extent by polished finish, wood float finish, coarse or fine sand, white 
sand, red sand, yellow sand; further there is the scagliola finish, but it is, of course, 
very expensive; the cement can also be tinted a brick red and jointed, and a brick 
finish obtained. Two to one of sand and Portland cement is best for rendering. The 
cement should be plastered in the ordinary way but with greater pressure than for 
ordinary plaster, indeed, the more pressure the better. The best form of colouring 
should be coloured sand. 

12. For rendering 3 : 1 Portland cement mortar finished with a facing coat of 2 : 1 
has been emploved. 

13. A good effect is obtained by removing the mould as soon as it is safe to do s,> 
and brushing vigorously to expose the aggregate, which may be the same throughout 
the body of the concrete or special aggregate in. the facing only. Good effects are also 
obtained by using stone dusl with the sand for rendering buildings. Render in coats 
about ) in. thick, then trowel. The following coat- should be put on as soon as 
preceding coat has gone off. 

14. Brushing the surface of the concrete before it is set to remove the cement skin 
is advocated. 

15. To lace concrete without rendering a creamy liquid mixture made of 1 part of 
Portland cement and I a part of white, clean, sharp river sand has been squirted on the 

388 



l&gSgESK^g SURFACE TREATMENT OF CONCRETE. 

surface through a rose nozzle ;;n<l applied in two coats, the second coal being put o 
hours alter the first. A rendering of a plastic mixture of i pari ol Portland ' 
\ a part of clean white river sand pulverized and reduced to a consistent with 

lime-water has been applied with a trowel. The surface of the concrete work should be 
thoroughly wetted with lime-water and picked h>r at leaSl three hours before either the 
squirting process or rendering process is employed. Stucco plastering work, resembling 
marble, may be laid in three coats, the colour being obtained b\ mixing gypsum to 
lime and certain metallic oxides. Blue is obtained b\ oxides or carbonate of copper. 
Cnvy is obtained by mixing forge ashes; litharge, yellow oxide of lead, green enamel, 
etc., are also used to colour it. A polished surface has been obtained by rubbing the 
surface with a line smoothing stone, washing it now and again, and rubbing with a 
linen dipped in Tripoli powder and chalk, then with oil and Tripoli powder, lastly oil 
alone. 

16. A good surface may be obtained by working with a spade perforated with holes 
up and down against the shuttering. 

17. Before applying rendering, the walls require to be hacked and well wetted. To 
avoid cracking, the rendering should be kept damp and protected from the sun and 
wind for about seven days after execution. A pleasing appearance can be had by 
dashing on the rendering white or straw-coloured sand composed of sea-shells; white 
cement and white sand also give an excellent finish. A pleasing and permanent tint 
can be obtained by a wash of quick-lime coloured with common sulphate of iron or 
copperas, which gives a light cream to a warm reddish yellow finish. 

18. The concrete should be made moderately wet, and well rammed and sliced with 
long trowels or swords to drive out the air-bubbles and to prevent any voids on the 
surface. Where a watertight face is desired — for example, in reservoirs or dock work — 
the shuttering should be coated with 1 : 1 cement mortar, about \ in. thick, immediately 
before the concrete is deposited and the concrete forced into this mortar. Fillets could 
be arranged on the shuttering in convenient positions to avoid showing breaks in live 
concrete deposited at different times — i.e., to give a jointed appearance. 

19. To face the concrete, the surface before it has become too hard should be 
rubbed with an old piece of the same material to remove form marks and general lines, 
and a wash of Portland cement then applied with a lime-wash brush. A mixture of 
red oxide to cement rendering has been found to retard setting and to tend to destroy 
adhesion. 

20. A good surface may be obtained by building at the same time as the body of the 
concrete a facing of sand and cement, or, better still, ground Portland cement, or 
ground sandstone and cement proportioned 4:1. The boarding should be removed at the 
earliest possible moment, and the surface well brushed with a strong wire brush. In 
time the surface will resemble Portland stone. 

21. For rendering 3 parts of washed sand to 1 of cement have been employed 
mixed with long clean ox-hair. It should be applied in two coats and the surface bit 
from a wooden float. 

22. A rendering of 2 parts of granite gravel § in. to \ in. gauge to 1 of cement is 
satisfactorv, but is better applied before the body of the concrete has set. 

23. Rendering may be proportioned 1 : 1 to 1 : 4, but usually it is about t : 2. 

24. Forms or shuttering may be coated with a lime-wash made of pure lime, 
slaked with boiling water and applied when hot. Before application a large cupful of 
linseed-oil or tallow should be added to each pailful of hot lime; this ;is-ists in closing 
the pores of the wood and prevents the adhesion of concrete. 

2^. In executing concrete wthout rendering, if the boards are planed and covered 
with thick oil paper the surface is good enough for whitewashing. The best rendering 
is cement and sand outside and putty and plaster inside. 

26. Rubbing down with sand and water while the concrete is still green is 
advocated. If rendering be employed, Thames sand washed and screened through a 
trj-in. mesh to 2 parts of Portland cement is a good mixture. 

27. Granitic finish is obtained by 2 parts of granite chippings, \ in. gauge with a 
proportion of granite dust, to t of Portland cement. For vertical rendering mortar 
screeds are employed, but lor horizontal granitic facings wood screeds are g< n 
employed. Aberdeen or other coloured chippings give a pleasing effect for floors. 

28. For country buildings rough-cast or pebble dash of cement and sand, with a 
small proportion of run lime therein, about an inch thick, after stabbing a straight 



SURFACE TREATMENT OF CONCRETE. (CONCRETE] 

coat of cement and sand with a piece of wood having shorl nails fixed therein, 
projecting about \ in. and J in. apart, the walls whitened or coloured after, is advocated. 
The cement protects the concrete from drifting rains. Several other processes have been 
tried with indifferent success. Pieces of wood 4 to 5 in. wide and 1 in. thick fixed to 
the concrete to represent half-timber work, and cemented between to form panels for 
a lodge very much exposed to drifting rains was easy to do and answered its purposes 
— but a sham. Cement and slag from iron ore, crushed and passed through &-in. sieve 
instead of ordinary sand, proved very successful for rendering. The surface was much 
harder and the colour more a dark grey, and was preferred to the ordinary cement 
colour. 

29. Rendering is objected to. When appearances have to be studied, a 4^-in. brick 
wall is built and filled at the back with concrete, a heading course to bind in being 
built occasionally ; by this method expense of shuttering is saved, the concrete being 
placed after three or four courses of bricks are built. 

30. Bv using waste quartz and mica sand and gravel from china clay preparations 
if the moulds be quickly removed, and the surface washed with scrubbing-brushes and 
water, it will have the appearance of white granite. 

31. A good appearance can be obtained by removing the moulds quickly and 
brushing with a wire brush and water; if the concrete has become hard, some dilute 
hvdrochloric acid must be used to remove the cement. If a smooth surface is preferred, 
the moulds can be removed after the concrete has been deposited, and the surface 
rubbed over with a wooden float to remove inequalities, after which a thin grout of sand 
and cement of the same proportions as the mortar in the concrete can be applied with 
a cork float. 

32. For inside a thin skimming coat of 3 parts of sand and 1 part of lime putty, 
and with 25 per cent, of Portland cement added, has been found satisfactory; for 
external rendering 1 of cement and 3 of sand is advised. 



In the discussion which followed, some interesting points were raised, which we 
trust will have the careful consideration of the Committee dealing with these questions. 
In the course of his criticism of the two reports, Mr. Alban N. Scott made reference to 
the constant use of the word " crazing," which in the first report evidently meant a 
form of crack, and in the second report was used probably in its more true sense, 
namely, meaning " flaking off." He also disagreed with the suggestion that concrete 
should be fairly liquid and the advocacy of bringing the finer particles to the face of 
the concrete. He showed that according to the first report this latter recommendaiion 
caused " crazing " and cracking, and, moreover, he pointed out that it is robbing the 
concrete, which is actuallv carrying the weights, of its proper proportion of cement. 
He further discussed the question of dates for the removal of the centering and moulds. 
He thought it quite wrong to remove the moulds quickly, in order to obtain a good 
appearance, as this practically amounted to sacrificing strength and durability to effect. 
He questioned the dressing of the concrete with hand or pneumatic operated chiseld 
and hammer. He also made suggestions regarding the removal of forms for walls 
and arches, sides of beams, etc. He pointed out the ambiguous use of the expressions 
" moist air " and " dampness " in connection with steel, and suggested it should be 
clearly defined what was meant by them. Finally, he spoke at some length on the 
question of expansion joints as dealt with in the reports. 

Dealing with the report on the Surface Treatment of Concrete, Mr. Percival M. 
Fraser said he sympathised with the views of a previous speaker, and had Imped more 
would be said about surface treatment, which means treating the surface after it is 
there, whereas the Report apparently aimed at putting a surface on, which is not in 
accord with its title. Nothing is said about weather-proofing the surface. Some recom- 
mendations as to how to avoid honeycombing would have been invaluable, as it is a 
very common fault. Only a passing reference is made to this in the report. The 
method of obtaining a good surface by working up and down the shuttering with a 
spade; the application of a mixture of sand and cemenl to the inside of the moulds were 
strongly criticised. 

One method of obtaining a nice-looking surface to concrete is not mentioned in the 

39° 



Rg gggggRSE^ DISCUSSION. 

reporl al all, viz., the application of a good coal <>! distemper, which should ' 
on immediately the centering is struck and a further coat should be applied just ; 
leaving the work. 1'- has an extraordinary effect in filling up pores, and any tint can 
be used. Some buildings have recently been put up in Jamaica and the surface tr< 
in thi> manner and they looked delightful. No reference is made to th<j saf< 
painting concrete, which is an obvious method for finishing off the surface. 

Another speaker said lie had been rather hoping that the reports had mad. some 
mention of the various patents for rendering the surface of concrete waterproof. 

A suggestion as to waterproofing was put forward by Mr. Henry J. Harding, who 
advocated a really good blue lias lime, thoroughly burned and more thoroughly selected, 
perfectly divided and mixed in its dry state with Portland cement in a certain 
proportion — viz., i : 3 or 1 : 4 in its hydrated state, which is about 2^ times more than in 
its caustic state, with 3 or 4 of cement. 

The same speaker gave details of some interesting experiments he had made with 
graded granite chippings. 

It was stated by the President that if concrete is properly proportioned and made, 
it is absolutely impervious to water, and where it is found not to be waterproof it is 
badly proportioned and badly made with an insufficiency of cement. He also related in 
some detail his experiences about the striking of the shuttering, and pointed out 
there were cases where the shuttering had been struck on structures 130 ft. high in 34 
hours without detrimental results; on the other hand it is doubtless often advisable to 
leave it up as long as possible in the case of certain walls. At this point Mr. Alban 
Scott interposed, and said that even if such be the case, in a report of this kind, — which 
is probably to be issued to people who are not so conversant with the question, — some 
cautioning clause should be inserted. 

d'he various criticisms put forward were replied to at length by Mr. Workman, 
who assured those present that all the suggestions made would receive careful 
consideration. 



F. MENCL. 



fCDNCB EIl] 









jggpgpa^^g* 



i 



fir iMr^ irfifep ^ ; - w&*&frf - 






V 



^v :■ 




THE 
REINFORCED 
CONCRETE 

BRIDGE OVER THE MOLDAU, NEAR THE ISLAND 

OF STVANICE, WITH SOME HISTORICAL NOTES 

ON THE OLDER BRIDGES OF PRAGUE. 

By F. MENCL, 

Engineer-itt-Chief, Prague. Municipal Commission of Public Ways. 
(Translated!. 

An important bridge has recently been erected in Prague, the form of construction being 
Reinforced Concrete, and, as much difficulty ivas encountered in the ivork, the following 
particulars of the neiv bridge, ivith some historical notes of Prague's older bridges, may not 
come amiss. — ED. 

Historical. 

There are many bridges in Prague which are of considerable interest. As far 
back as 1 169-71 a bridge was erected in stone 514 in. long. This was one of 
the first large arched bridges of the Middle Ages. This bridge had but a short 
existence, for it was washed away and demolished by a flood in 1342, but of its 
twenty-six arches three have been preserved in the cellars of the houses on the 
bank of the river. 

In 1357 King Charles IV. ordered that a new bridge be constructed, and 
this now bears his name. This bridge consists of sixteen arches, and it, too, 
suffered several times through floods, as its foundations lacked depth, but it 
has always been kept in repair. On the last occasion on which it was restored, 
after the flood of 1890, the repairs cost nearly 2,500,000 francs. (For illustration 
sec page 401.) 

The three Gothic towers which are to be found at either end of the bridge, 
and the double row of statues of the " Baroque " period which decorate its 
parapets, form some of the most remarkable monuments of Prague. 

Until the nineteenth century the Charles IV. bridge was the principal bridge 
in Prague. It was not until 1846-50 that Xegrelli, a Swiss engineer, executed 
the double-way viaduct, of 1,100 m. in length, which connects the State railway 
station to I lolesovicc. 

In t868 the suspension bridge, called " Ordish-Lefevre, " was erected with 
two lateral spans of 50 m. and a central one of 150 m. This was reconstructed 
in [897, and the primitive chains were replaced by cables. 

': he Palacky bridge, of stone construction (named after the Czech politician 
and historian), was erected in [876-78. lis seven arches are from 27 m. to 
32 m. wide. Beautiful statues (by Mvslbek) decorate its approaches. 

The Francis I. bridge, which in 1898-1900 replaced a suspension bridge, 
has eight stone arches with a maximum width of 42 m. ; it is 540 m. long and 
16 m. wide, and the net cost of erection was somewhere about 4,100,000 francs. 
The form of the arches recalls those of the Alma bridge in Paris. 

39 2 



ON.STHIKTIONAi; 
ENGINEERING—, 



I»7con7 

L< V ENGl 



REINFORCED CONCRETE BRIDGE. 



The railway bridge near Vysabrad did not improve the district with its 
three bowstring girders of 72 m., and this type of bridge is nol worthy of an 

ancient capital. 

The bridge named after the poet Svatopluk Cech was constructed in 
1905-8. It has metal arches with rigid spandrils of 48 m., 53 m., and 59 m. 
in width. 

But sufficient of history, as it is principally the new reinforced concrete 
bridge near the island of Stvanice which is under review here. 




Detail of Pier of Bridge over the River. 
Reinforced Concrete Bridge over the Moldau, Prague. 

The New Reinforced Concrete Bridge over the Moldau, Prague. 

For a long time a certain amount of prejudice existed in the large cities 
against reinforced concrete bridges. Where such bridges were built the con- 
crete facades were carefully covered with freestone, as, for example, in the case 
of the new' bridges of Munich and Dresden. Therefore the decision to construct 
a bridge entirely in concrete in an ancient capital must be looked upon as a new 
departure. 

It must be admitted that the work did not proceed without overcoming 
some obstacles. Owing to prejudice, one half of this bridge was constructed 




Detail of Arch Centering of Bridge over the River. 
Ri inforced Concrete Bridge over the Moldau. Pragui 

with metallic arches in 1908-9 (two spans of 46 m.), in spite of the fact that a 
concrete arch design had been prepared. Hut the new bridge over the large 
arm of the Moldau, with its facades made to imitate stone, its balustrades, 
masts, plastic decoration, and sculpture, was built entirely in concrete. 

This bridge is divided into two sections : the one traversing the river at a 
height of about i2'5o m. at low-water mark, and comprising three large arches 
of 39 and 36 m. span, with an inclination <>f 69 ; the other section, over the 



F. MENCL. 



[ CONCRETE] 



island of Stvanice, is 7 m. high and comprises four small arches 17-85 m. span, 
the angle of inclination increasing here from 69° to 75 . 



- -^ 



i 




-■ 


T~T 




H 




















1 — 












r*~ 
























* ^ 










i 


Tt" 










1 


r 






















tl 















The foundations of the piers and abutments for the large arches were 
((instructed with the aid of dams and dired pumping; the rock is uncovered at 
the bottom of the river where it is not very deep. 
39+ 



I g T CONSTKUCTIONAIJJ 
1A ENGI>J Et.R I NO — .j 



REINFORCED CONCRETE BRIDGE. 







w*$ - 



39S 



f. mencl. [CONCRETE] 

The large arches are of concrete without reinforcement, as there were 
various prejudices against reinforced concrete, and at Dresden and Munich- 
towns not far from Prague — large concrete bridges had already been erected 
without reinforcement. Such bridges very closely resemble stone bridges, and 
these always inspire confidence among the general public. (A new one at 

P r a g u e, 
near Troja, 
f o r w" hi c h 
the design 
has also 
b e e n pre- 
pared, is to 
have a cen- 
tral arch, of 
55 m. , of 
r e i n f orced 
concrete rib 
cons truc- 
tion, which 
m u s t be 
considered a 
d e c i d edly 
> p r ogressive 
~ step.) 

The 
h links of the 
« big" arches 

o consist o f 

u 

a lead plates 

5 of 10 mm. 
\ thic k n ess, 

6 which are 
200 m m. 
wide at the 
k e y s t o n e 
and .240 mm. 
wide at the 
all utments ; 
these are in- 
serted be- 
tween blocks 
of granite. 

The thickness of the arches is 75 cm. at the crown, 90 cm. over the abut- 
mi nts, and 105 cm. at the quarters. The neutral axis of the arches coincides 
with the curve ol pressure lor the {\vai\ load. 

The relieving arches over the piers have been suggested by the Am 
bridge at Toulouse. They serve lor the decoration ol 
motif lias been sought, so that the bridge may be soniel 




uli miners 
ie work", and a new 
iim>- distinctive from the 



396 



[/, CONSTPlKTIONAl.l 
1A ENOlNfcr.KINCi —J 






REINFORCED CONCRETE BRIDGE. 

m m w 







F. MENCL. 



[CONCRE TE] 



preceding ones and those still to be carried out. (At the present moment a 
four-arch bridge is being" built of 38 and 42 m. span.) They broaden con- 
siderably towards the abutments, so that the loads arc not concentrated locally. 
The available width between the inner faces of the parapets is 1620 mm., 
the roadway being 10 m., with two pavements of 3' 10 m. 

As the arches only have a width of 15*90 m., the parapets are carried in 
cantilever. 

The main spans have been executed in three zones of 6 m. and 795 m. 
width, in contact, but distinct. There was a twofold reason for this. The 
arches are very oblique, and this simplified the work. It was, as a matter of 
fact, possible to concrete one zone of each arch in four or five days, and therefore 

a zone onlv consists of six 
large voussoirs. If, on 
the other hand, the arch 
had been carried out in 
one single zone of 
15'cp in., it would have 
been necessary to have a 
large number of narrow 
voussoirs. 



' 55 







The piers have a 
width of 4 m. at the abut- 
ments and are 1 : 8 con- 
crete, faced with dressed 
granite back and front, 
with small ashlars on the 
sides. 

The left and right 
foundations are respec- 
tively io'70 m. and 9 m. 
wide, but the concrete is 
fairly poor — namely, 
1 : 12. 

The small arches 
over the Stvanice Island 
are somewhat irregular. 
The abutments are on 
a line sloping at 1 : 215, and the piers are not parallel, as the angle of inclina- 
tion increases from 69 to 75 . The opening downstream is therefore 45 cm. 
larger than upstream. It would have been simpler to widen No. 4 pier down- 
stream, but the method adopted makes the bridge lighter, and lias gone to 
prove that the use of concrete permits of this form of construction being 
employed with ease, whereas il would have been very difficult: if carried out in 
carved stone or metal. 

The reinforcement of the lower and upper surface ol the small arches 
consists of rods 20 mm. in diameter and 15 cm. apart. The thickness at the 
crown is 35 cm. The intermediate piers (Nos. 5, 6, and 7) and the abutment, 
No. 8, have foundations of about 5 in. depth, and are buill on wooden piles. 
308 






Detail of Arch over the River. 
Reinforced Concrete Bridge over the Moldav, Prague 



fa, tK3NSTPl)CTiONAl. 
1 A ENGINEERING — , 



REINFORCED CONCRETE BRIDGE. 



Plain filling lias been used over the arches between the facing walls. 

The bridge carries a water main of 380 mm., a gas main of 410 mm., and 
electric cables. 

The masts carrying the electric lights and trolley wires of the tramway 
are also in c< ►ncrete. 

We consider that it is a progressive step that the bridge has not been 
covered with stone, but that the entire facade should be covered with a layer 
of finely crushed marble-concrete about 6 cm. in depth. This laver is not 
smooth, but has a roughened surface to imitate stone. The lower surface of 
the arches has been squared and finished by means of simple wood moulds. 

The foundations for the piers were started in April, 1910, and the work was 
carried on in such a manner that it was possible in October, 1910, to construct 

.-... the four 



ST: 1; V. l 

>'■■.'■•■''-•■ : -''. : ' .-■■■■■ ■ ■■■/■ ■-■•r. ' 




arches over 
the island. 

T h e y 
were rammed 
o n October 
10th, 15th, 
2 1 st, a n d 
26th respec- 
tively. The 
cente ring 
was removed 
on Decem- 
ber 9th, and 
the deflec- 
tion w a s 
about 
04 mm. 

The 
columns for 
t h e large 
arches were 
completed in 
May, 191 1. The centering presented a certain amount of difficulty — firstly, 
on account of the navigation, as it had been ordered that an opening of 14 m. 
should be left. Further, the bed of the river consisted of layers of Silurian 
rocks, and it was necessary to fix the piles to old rails embedded in the rock. 
The centerings had sixteen main struts. 

The arches were commenced on June 21st, and were successively rammed 
on July 15th and August 2nd and 22nd. 

Each arch was divided into sections, the ramming of which was carried 
out by commencing with the part nearest the crown, then the abutments, etc. 
The concreting of each section was completed on the same day. During the 
work the centering dropped 44, 50, and 58 mm. 




Detail Section through Roadway of Bridge. 
Reinforced Concrete Bridge over the Moldau, Prague. 



399 



f. mencl. [CONCBEX FJ 

According to the design, the surface of the granite blocks in contact with 
tlie lead sheets was to be polished, but it has been left fairly rough. As too 
much deflection was feared, it was decided to compress these hinges before 
concreting by means of hydraulic presses. The pressure applied was 30 tons 
(about 30 per cent, of the definite maximum pressure). 

The lead hinges are placed 2 cm. out of centre at the crown ; they are 
below the middle line and above it at the abutments. 

In each system of links there is friction displacing the resultant from the 
centre ; in this manner it is possible to destroy in part the influence of friction. 

Steel links, 30 mm. in diameter, were employed at the grooving joints to 
act as anchors (twelve links to each arch). Where an arch is on the skew, it is 
always preferable to place anchors, especially in this case, where the arch is 
hinged and on the skew, and has no continuous axis of rotation, and thus tends 
to separate at the zones. 

To prevent dampness, two layers of felt asphalt have been placed on the 
upper surface of the arches, with a thin intermediary layer of lead (o'i mm. 
thick). 

On September 25th, 191 1, the removal of the centering was commenced, 
with the aid of a Zuffer apparatus. The deflection was from 1 to 4 mm. in the 
extreme arches and 6 to 10 mm. in the three zones of the centre arch. 

The cement used acquired a resistance of 505 to 617 kg. per sq. cm. at the 
end of twenty-eight days. The 1 : 4 granite concrete attained a resistance of 
606 kg. per sq. cm. for cubes of 20 cm. side. 

The bridge was tested from February 3rd to 6th, 191 2. (During these 
davs the thermometer fell to 16 C.) The central arch of 39 m. and a small arch 
over the island were tested. Two street rollers of 19 and 16 tons respectively 
were used in conjunction with eight 13-ton wagons. The rest of the load 
was made up with bricks (500 kg. per sq. m.). The main arch showed a deflec- 
tion of 1 mm. with one-half the load, and 1*5 mm. under the total load of 
337 tons. The small arch deflected C7 mm. 

The total construction contains 12,350 cu. m. of masonry : — 

Concrete 10,570 cu. m. 

Quarry stone (rough) 970 ,, 

Dressed Stone (granite) 540 ,, 

Quarrystone (dressed) 180 ,, 

Brickwork 90 ,, 

The carved stonework is only 4 per cent, of the total cubic measurements. 
The concrete was mixed as follows : — 

Foundations 1 : 12 4.050 cu. m. 

Piers and Columns ... 1:8 3,000 ,, 

Piers and Columns ... 1:6 750 ,, 

Large Arches 1 : 4 2,050 ,, 

Small Arches 1 13 740 ,, 

The Steel lor the reinforcements weighs 90,800 kg. The lead for the joints 
weighs 3,340 kg. 

The net cost of the bridge has worked out at a total charge of francs : 
1,142,000. This price is comparatively low, as the other bridges in Prague 
400 



fy..(XiN> 



TBIKTIONAL1 
,lTNLEmNO_2~J 



REINFORCED CONCRETE BRIDGE. 



which are of stone or metal have cosl from 750 to 850 fi u r sq. m., 

whereas the one here described works ou1 at 350 francs per sq. m. 

It should be added that the bridge has a pleasing appearance (especially 
compared with the steel arch bridges), and the foremost of the young Czech 
sculptors are at work on its decoration, which is not yet finished. 

The bridge was designed by the writer at the offices of the Prague Municipal 
Commission of Public Ways. The architecture is the work of Mr. 1*. Janak, 
and the contractor was Mr. K. Herzan. 




View of the Charles IV. Bridge at Prague. 



4OI 



A. T. WALMISLEY. 



[CONCRETE? 




By A. T. WALMISLEY, M.Inst.C.E. 

{Engineer to the Dover Harbour Board.) 

In vieiu of the important position Dover holds, from a geographical point of vievo, the 
following article dealing "with the -widening of the Dover Pier mav claim attention. — ED. 



The stratigraphieal position of Dover has probably been more studied in the 
past than its strategical position. Its geographical position with regard to 
the Continent gives it premier importance for international communication. 

As early as the end of the third century Dover was acknowledged to have 
been a place of note, but the commencement of the history of Dover as a 
harbour of refuge is claimed by the fifteenth century. Soon after King 
Henry YJI.'s accession he assisted John Clark, Master of the Maison Dieu, to 
add to the natural headland a wall of chalk filled in with earth, and to build 
at its extremity a tower, with the addition of mooring rings, and such was 
the satisfaction given by John Clark's wall that the haven providing shelter 
from prevailing south-west winds received the name of "Little Paradise." 
The wall was strengthened and secured by the natural deposit of shingle from 
the west, and was intact when King Henry VI 1 1, came to the throne in 1509. 
Later on an extension of the wall became necessary in consequence of the 
accumulation of shingle closing the entrance of the harbour — a trouble repeatedly 
experienced during many generations until the Admiralty Pier was constructed 
in the latter half of the nineteenth century. King Henrv VIII. spent a large sum 
on work designed to prevent the beach collecting at the harbour mouth and 
stopping the passage of vessels. With this object he brought by water-carriage 
blocks of stone and chalk, which were sunk to form a foundation, the intention 
being to build a mole, or pier, seawards; but prior to its completion other 
demands on his revenues compelled him to abandon this undertaking. The 
unfinished work remains to this day, and is locally known as the mole rocks, 
situated near the present north pier to the inner harbour. 

In 1581 tin- Passing Tolls Act was passed for the benefit of Dover Harbour. 
By this Act, for every vessel owned or parti}- owned by subjects of the Crown, 
of the burden of 20 tons and upwards, laden or discharging within the realm, 
and passing to or from any foreign country, a toll was levied. 

During the seventeenth century the raging question in Dover was 
undoubtedly the harbour, and King James L granted a new Charter, which 

402 







»„C0NM-UUCT10NAL' 
g ENGlNfcE-RlNG — , 



THE WIDENING OF THE DOVER PIER. 



stated in substance as follows : — The importanl Port of Dover had gone to 
decav and was deemed unsafe for ships. It recited that, as Royal patrons, 
Kings Henry VII., Henry VIII., Edward VI., and Queens Mary and Elizabeth 

had expended large sums of money upon this port, and that King James I. was 
also determined to expend money in order to preserve it. A Lord Warden and 
ten assistants were appointed by the King - , with power to fill up vacancies on 
the board as they occurred, for the government of the whole property of the 
harbour, with the care of land, houses, buildings, cranes and wharves; and 
under their Charter, with some additional Parliamentary powers, the harbour 
was governed till 1861. 

In 1610 passing tolls expired by efflux of time, after which Dover Harbour 
had to depend upon tolls, dues and rents until 1662, when passing tolls were 
renewed and extended during the reign of Queen Anne (1702-1714). 

The date of the seal of the present Dover Harbour Board is 1646. 

In 1769 John Smeaton, the eminent engineer, reported upon Dover harbour, 
but from lack of funds nothing was immediately done. 

The ''Public Advertiser" dated April 13th, 1792 (published at Ivy Lane, 
Paternoster Row, London), contains a quotation from an evening paper dated 
March 19th, describing Dover Harbour as being " naturally one of the best in 
the kingdom," but points out that the entrance is too shallow and that the bar 
then existing should be removed. 

A line of sailing boats between Dover and Ostend was then crossing, 
weather permitting, twice a week. 

In 1844 a Royal Commission reported on the area, outline and materials 
recommended for an artificial harbour at Dover, together with comments on the 
position and desirable width of entrance to an enclosed area of 520 acres to 
form a harbour of refuge; and in 1846 a further report recommended the 
prescribed area of 520 acres to be considered a minimum requirement for the 
harbour of refuge at Dover, also that an eastern and western entrance be 
provided so as to permit a free tidal current through the harbour, with a 
southern breakwater placed as nearly as possible in the direction of the flood 
tide, and in a depth of seven fathoms at low water level. 

Prior to the commencement of the Admiralty Pier in 1847 the harbour was 
frequently inaccessible owing to the bar formed near the entrance, when vessels 
had to lie off in the bay. It is of interest to note that while the concrete blocks 
used upon the Admiralty Pier as originally constructed were three to seven tons 
in weight, the blocks in the Admiralty Harbour as now constructed weigh 
42 tons as used in the foundations. 

In 1861, when the London Chatham and Dover Railway was opened, we 
find the final abolition of passing tolls, and the control of Dover Harbour is 
transferred from the Warden and assistants, as constituted by King James I., 
to a Harbour Board consisting of the Lord Warden of the Cinque Ports, two 
burgesses of Dover chosen by the Town Council, one representative each of the 
Admiralty, of the Board of Trade, and of both the South Eastern Railway 
Company and of the London Chatham and Dover Railway Company. The 
London Chatham and Dover Railway Company took up the Mail Service. 

4°3 



A. T. WALMISLEY. [CONCRETE] 

Captain Morgan was the first Marine Superintendent under the London 
Chatham and Dover Railway Company. He was thirty-five and a half years in 
this office, and was succeeded by Captain Dixon, the present Marine Superin- 
tendent at Dover and Folkestone. 

Among various forms of passenger steamships we find the Bessemer steam- 
ship, which was an independent venture. The Castalia also was extra to the 
Mail service, but its speed was insufficient. The original Calais-Douvres' 
boiler and funnels soon wore out, and its speed was only 13-2 knots. 1 he 
Invicta, with double rudder, could not conveniently turn in Calais Harbour. 
Several other vessels of the paddle or ordinary twin-screw type followed. 

In 1882 the Dover Harbour Board obtained an Act for works in connection 
with a deep water harbour, but the works were subsequently postponed pending 
the Government's consideration of a national harbour. 

Referring to the inner basins of Dover Harbour, its existing extrance, 140 ft. 
between timber framed piers filled with rubble stone to high-water level, leads 
to a tidal harbour having an area of about 13^ acres, including the area of this 
entrance passage. Situated in the inner harbour, the Granville Dock has an 
area of about 4! acres within the gates, and the entrance is 65 ft. wide, with 
21 ft. clearance over sill at high-water spring tides. The Wellington Dock has 
an area of 8J acres within the gates, and the entrance of 70 ft. wide, with 
15 ft. clearance over sill at high-water spring tides. 

In 1891, the Dover Harbour Board obtained Parliamentary powers to levy 
a poll tax of is. a head on passengers landing or embarking at Dover, in order 
to provide funds for an eastern pier, commencing near the Clock Tower, to 
form the eastern arm of a proposed deep-water harbour, and to provide shelter 
for a site for a Marine Station on land to be reclaimed from the sea to the east 
of the Admiralty Pier, also to abandon certain works for which powers had 
already been obtained. This policy became urgent, as there appeared at the 
time no certainty that the shelter of a Government harbour would ever be pro- 
vided upon the south and east of Dover bay, and under this Bill power was 
obtained for the extension in an easterly direction for a distance of 580 ft. or 
thereabouts, to form the western head of a commercial harbour, leaving an 
entrance of 450 ft. between the pier heads. 

In 1892 the Dover Harbour Board let a contract to Sir John Jackson for 
the Prince of Wales Pier works. The shoreward end of this pier, for 1,260 ft., 
is formed by an iron viaduct, to allow the tide to run through, with a clear 
headway of 75 ft. above high water, on the supposition that no outside sea- 
works would then be constructed. 

In 1897 the " Naval Works Act " included the building of the Admiralty 
Harbour enclosing the Harbour Board's eastern pier, and in 1898 the Dover 
Harbour Board obtained a further Act, extending the area enclosed by the 
piers upon the east and west sides, and having an entrance of 480 ft., between 
the then proposed head of the Prince of Wales Pier and the head of a spur 
suggested to be attached upon the eastern side of the Admiralty Pier extension. 

In 1900, the Harbour Board obtained an Act lor converting the tidal har- 
bour into a concourse basin, approached by a deep-water lock, and other 
proposed improvements, and in rcpo, at a reception by II. I. M. the German 

40+ 



I a. CONSTKUCTIONAU 
[A ENOINEEJilNC-r-3 



THE WIDENING OF THE DOVER PIER. 




&///■&. 4//^t'n&//-^- ** Scm " : of F " 1 

J't$ /&■**}/ J--^ > )'3k~y Spring Tides rise 18 3" 



Emperor al Potsdam, of a deputation of the Harbour Board, the Emi 
expressed the opinion thai Dover Harbour would become a convenienl port of 
call for the German Atlantic liners. 

In 1904 the first passenger train traversed the Prince of Wales Pier and 
its approach railway on January 27th, and in the same year the landing Stage 
upon the eastern side of the Prince of Wales Pier was subsequently used for 
the accommodation of Atlantic liners to call at Dover, railway communication 
being established by the Dover Harbour Hoard between this landing stage and 
the S.E. and C. Railway main line at Dover Harbour Station. The S.S. 
Deutschland, Hamburg-American Line, made her first call at the Prince of 
Wales Pier on July 22nd, 1904. 

In 1906 an Act of Parliament was obtained under which the Dover Harbour 
Board were empowered to 
render the Admiralty Pier 
(which was originally con- 
structed only as a break- 
water) suitable for the em- 
barkation and disembarka- 
tion of railway passengers. 
Bv the powers conferred in 
this Act certain works pre- 
viously authorised were 
abandoned, and agreements 
made between the Harbour 
Board and the Commis- 
sioners for executing the 
office of the Lord High 
Admiral of the United King- 
dom of Great Britain and 
Ireland, popularly known as 
" The Admiralty," also with 
the South Eastern and Chat- 
ham Railway Company, were 
confirmed. 

The turbine system, ap- 
plied by the Hon. Mr. Par- 
sons after having gained a 
fame on the River Clyde, 
was soon extended to the 
English Channel. The first 
vessel so constructed was the 
Queen, which was 310 ft. 
long, and the latest vessel of this type on order is stated to be 345 ft. long. 
The distinguishing feature of this system is the reduction of vibration to a 
minimum, while the manoeuvring power is manifest to all travellers. 

The Prince of Wales Pier forms the boundary between the Admiralty Har- 
bour and the Commercial Harbour, both within the Dock Yard of Dover, and 

4°5 




Main Light - 



DOVER HARBOUR. SHOWING RECLAMATION 



A. T. WALMISLEY. [CONCRETE] 

while the east side of this pier, which is about 2,910 ft. in length, is reserved to the 
Admiralty, the Dover Harbour Board have provided railway platforms on the 
west side for use when circumstances render it preferable to bring- the mail 
train by the Prince of Wales Pier railway to this pier, instead of upon the 
present Admiralty Pier. 

In 1909 the reclamation works east of the Admiralty Pier were commenced, 
designed to provide 11J pcres attached to this pier as a site for a railway station 
and sidings, and leaving 64 acres at low-water level for the purposes of the 
outer commercial harbour. This reclamation up to coping level has been 
executed by the Harbour Board. The marine station will be erected by the 
railway company on the reclaimed site, and will provide ample accommodation 
for Continental traffic. 

The modus operandi for the construction of the reclamation wall is as 
follows : — In the first instance a staging is built, formed of braced timber piers 
upon each side of and clear of the foundation site of the main wall. 
These staging piers are about 40 ft. apart and are buiit by aid 
of a cantilever pile driver, being subsequently connected by longitudinal girders, 
over which Goliath cranes travel. The same triple process has been adopted 
by Messrs. S. Pearson & Son, the contractors for the present recla- 
mation work, as was followed in the National Harbour construction. The 
range of spring tide is 18 ft. 9 in. and of neap tide 11 ft. The first operation is 
the removal of all soft material by large mechanical diggers or grabs, which 
are lowered either from the Goliath or by a floating crane. The grabs, which 
are open when lowered, have their projecting teeth drawn together in the sea 
bed by chain arrang-ements so as to bring the excavated material above water 
and deposit it in barges for dispersal at sea. Next follows the service of a large 
diving bell suspended from the Goliath, which enables the surface for foundation 
to be accurately levelled, and finally concrete blocks made by machinery are set 
in position by the helmet diver. 

The following description of electric travelling concrete mixer, designed by 
the late Mr. A. H. Owles, and built by Messrs. Jessop & Appleby Bros., Ltd., 
Leicester, is of interest in its provision of a very efficient plant, referred to in 
Transport in the following terms : — 

Before proceeding to describe the machines it may be well to direct atten- 
tion to the reasons which led Mr. Owles to devise this ingenious system. The 
objects to be attained were the perfect mixture of materials in correct propor- 
tions, which is essential, and the immediate delivery of the quite freshly made 
concrete into the block moulds; also (from an economical point of view), to 
ensure the work being- performed rapidly and economically as regards cost of 
labour. The importance of these conditions being unerringly fulfilled is evidently 
necessary when wc consider the vast mass of materials required for the making 
of concrete blocks, and that these blocks are now almost universally employed 
in the construction of harbours and docks." 

The mixing vessel, the capacity of which is one cubic yard, is of the well- 
known Messenl type. It is mounted on a strong steel-framed carriage, provided 
with two electric motors, one of which revolves the mixing vessel, whilst the 
other gives a traxelling motion to the carriage, so that the operations of 

406 



[&E^iNEEKiNg^-j THE WIDENING OF THE DOVER PIER. 

mixing and travelling can be performed simultaneously. The proper charges 
of materia